When you receive a legally binding PDF contract via email, the archaic process of printing the document, physically signing it with a pen, scanning it back into the computer, and emailing the massive, degraded JPEG file is incredibly inefficient and wastes paper. You do not need to download sketchy third-party applications to digitally sign paperwork. The native macOS Preview application contains a highly secure, built-in Signature engine that allows you to capture your physical handwriting and instantly inject it into any PDF document.
How to Capture Your Signature
Before you can sign a document, you must capture a digital copy of your physical handwriting. Preview offers two distinct methods for doing this: using the Mac’s built-in webcam, or using the glass trackpad.
- Open any standard PDF document using the Preview application.
- Click the Show Markup Toolbar button (the small icon shaped like the tip of a pencil) located near the search bar.
- In the secondary toolbar that appears, click the Sign icon (it looks like a small cursive signature).
- Click Create Signature.
A specialized capture window will appear, offering two tabs at the top:
- Trackpad Method: If you click this tab, your Mac’s glass trackpad will instantly transform into a digital drawing tablet. Use your index finger (or a rubber-tipped stylus) to physically write your signature directly on the glass. Press any key on your keyboard when you are finished.
- Camera Method: If writing on the glass feels unnatural, sign your name with a thick black pen on a piece of blank white paper. Hold the paper up to your Mac’s webcam. The neural engine will instantly scan the paper, digitally extract the ink, vectorize the lines, and remove the white background.
Click Done to permanently save this signature to your secure iCloud keychain.
Injecting the Signature into a PDF
Once your signature is safely stored in the system, signing future documents takes less than two seconds.
- Scroll through your PDF contract until you locate the designated signature line.
- Click the Sign icon in the Markup toolbar.
- A drop-down menu will appear displaying your saved signature. Click it once.
The signature will instantly drop into the exact center of the PDF page. Because the signature is a mathematical vector graphic (not a standard JPEG), it has a completely transparent background. You can click and drag the signature directly onto the printed line, and you can use the blue corner handles to perfectly resize the ink without it ever becoming pixelated or blurry. Press Command + S to permanently burn the signature into the document before emailing it back.