Sign PDF with Digital Signature Certificate using Adobe

Digital signing has become an essential part of modern document workflows. Instead of printing, signing, and scanning papers, you can now sign PDFs securely using a digital signature certificate. Unlike simply pasting an image of your signature, a certificate-based digital signature adds verification data that proves who signed the document and ensures it hasn’t been altered after signing.

In this step-by-step guide, you’ll learn how to create a digital ID, customize your signature appearance, and sign PDF documents using Adobe Acrobat Reader. The entire process is free, beginner-friendly, and only takes a few minutes to set up. Once configured, you’ll be able to digitally sign documents anytime with just a few clicks.

What You’ll Need Before Starting

Before we begin, make sure you have the required tools ready. The good news is you don’t need any paid software — everything in this guide uses free tools.

You’ll need Adobe Acrobat Reader, which allows certificate-based digital signing. You’ll also need a PDF document to test the signature. Optionally, you can use a simple image editor like Paint if you want to create a cleaner handwritten signature image for a more professional look.

Download Adobe Acrobat Reader below:

Once Adobe Reader is installed, we’ll create your digital signature certificate in the next step.

Step 1: Create a Digital ID in Adobe Acrobat Reader

Before you can digitally sign a PDF, you need a Digital ID. Think of it as your personal signing certificate. It stores identity details like your name and email, and it’s used to verify that the signature really belongs to you.

Open Adobe Acrobat Reader and follow these steps:

1. Click Edit in the top menu
2. Select Preferences
3. From the left panel, click Signatures
4. On the right side, find Identities & Trusted Certificates
5. Click the More… button

A new window will open.

6. Select Digital IDs from the left side
7. Click the Add ID icon (looks like an ID card with a + sign)
8. Choose A new digital ID I want to create now
9. Click Next

Now fill in your details:

• Full Name
• Organization (optional)
• Email Address
• Country/Region

Leave the advanced settings as default and click Next.

You’ll now create a password to protect your Digital ID. This password will be required every time you sign a document, so choose something secure and memorable.

After setting the password, click Finish.

✅ Your Digital ID is now ready. In the next step, we’ll create a visual signature image so your digital signature looks like your real handwritten signature.

Step 2: Create an Image of Your Handwritten Signature (Optional)

Your digital ID already allows you to sign documents securely. But if you want your signature to look like your real handwritten signature, you can create a clean image file and attach it to the certificate appearance.

This step is optional, but it makes signed PDFs look much more professional.

Method 1: Draw inside Adobe (quick method)

1. Open any PDF in Adobe Reader
2. Click the Sign icon (pen icon)
3. Choose Add Signature
4. Select Draw
5. Draw your signature using your mouse
   • If you have a touchscreen or stylus, use that instead
6. Click Apply

Place the signature anywhere on the page temporarily.

Take a screenshot of the signature and paste it into Paint. Crop tightly so only the signature remains. Save it as a JPG or PNG file.

Method 2: Scan a real signature (best quality)

1. Sign on white paper with a dark pen
2. Take a photo or scan it
3. Open the image in Paint
4. Crop the background cleanly
5. Save as JPG/PNG

Now you have a clean signature image ready.

In the next step, we’ll attach this image to your digital certificate and customize how your digital signature appears on signed PDFs.

Step 3: Customize the Appearance of Your Digital Signature

Now we’ll link your handwritten signature image with your Digital ID. This step controls how your digital signature will look when placed on a PDF.

Open Adobe Acrobat Reader and follow these steps:

1. Click Edit → Preferences
2. Select Signatures from the left panel
3. Under Creation & Appearance, click More

A signature appearance window will open.

4. Click New
5. Enter a name for your appearance (for example: My Signature)
6. In the Configure Graphic section:
   • Choose Imported Graphic
   • Click File
   • Select the signature image you created earlier

Now customize the text details:

7. In Configure Text, choose what information should appear:
   • Name
   • Date
   • Location
   • Reason (optional)
   • Labels

Most people keep Name + Date enabled.

8. Click OK to save the appearance.

✅ Your digital signature style is now ready.

In the next step, we’ll place the actual certificate-based signature onto a PDF document.

Step 4: Sign the PDF with Your Digital Signature Certificate

Now we’ll place your secure digital signature on a document.

Open the PDF file that needs to be signed in Adobe Acrobat Reader.

1. Go to Tools
2. Select Certificates
3. Click Digitally Sign

Your cursor will change to a crosshair.

4. Scroll to the area where the signature should appear
5. Click and drag to draw a small rectangle

A signing window will appear.

6. Select the Digital ID you created earlier
7. Click Continue
8. Choose the signature appearance you customized
9. (Optional but recommended) enable
   👉 Lock document after signing
   This prevents further edits
10. Enter your Digital ID password
11. Click Sign

Adobe will now ask where to save the signed copy.

Choose a filename and click Save.

✅ Your PDF is now digitally signed.

You’ll immediately see your certificate-based signature on the document. Anyone who receives the file can verify that it’s authentic and hasn’t been modified after signing.

Important Reminder

If you enabled Lock document after signing, the PDF becomes read-only — even for you. Always keep an unsigned backup copy in case edits are needed later.

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