How to sign a PDF without a printer or a scanner

Got a contract or some other document that you need to sign and return via email? Well, you could always print it out, sign on the dotted line, scan the newly-signed document, and then send the new version as an email attachment—an effective, if cumbersome process.
Another, better option: snap a photo of your John Hancock with your Mac’s iSight camera (just about any recent iMac or MacBook should have one), then paste it into the document you need to sign.

All you need is latest version of Preview, the Mac software that lets you open photos, PDFs, Word files, and other documents.
[Note: Your Mac needs to be running on "Lion," the new version of the Mac operating system, for this feature to work.]
Here’s how to get started.

• First, open a PDF you want to sign using Preview. Just right-click on the document, hover your mouse over the “Open With” option, then select “Preview.”
• Now that the document is open, click the View menu at the top of the screen and select “Show Annotations Toolbar.”
• Right in the middle of the toolbar that appears, you’ll see a little, italicized “S” with a line through it, right next to a tiny downward arrow (as opposed to the “S” with the strikethrough line on the left). Click it, and select the “Create Signature from Built-in iSight” option.
• A window titled “Signature Capture” should appear—and if your iSight camera is working properly, you should see yourself sitting there, staring at the screen.
• Next, you’ll need a sheet of blank paper. Got one? Sign your name, and then hold it up in front of your Mac’s iSight camera lens. (Look for the little green indicator light above your screen.) Move the paper until you see your signature sitting just above the blue line.Once Preview has what it think is a good shot of your signature, it’ll appear in the “Signature Preview” window—and yes, you can go ahead and put the paper down.

Just hold up a piece of paper with your signature and let your Mac scan it with its built-in iSight camera.
• Everything looking good? If so, click the “Accept” button.
• Go back to the “signature” button in the Annotations Toolbar at the top of the Preview interface, click it, and select the signature that you just scanned.
• Move your cursor down to the dotted line in your PDF, and hover over it until you see part of the line turn blue. Click, and a tiny image of your signature will appear, surrounded by six little gray “handles.”
• Click on one of those handles and drag it open to resize your signature until it fits on the signature line.
• All set? Select File, Save Version at the top of the screen.

That’s it! Now you can save, print, or email the signed PDF as you see fit, no scanner required. You can also saved your scanned signature for future use, or delete it if you don’t want it sitting on your hard drive.