Insert your signature in OS X Preview

Apple Preview allows you to sign PDF documents with your FaceTime Camera using Mac OS X Lion or Mac OS X Mountain Lion.

1. click the button for the edit toolbar
2. click the signature button
3. click "Create signature…"
4. write your signature on a plain piece of paper and hold it up to the camera
5. click Accept
6. click in your PDF document to insert
7. resize and position your newly inserted signature

Once saved, you can reuse your signature any time.