Preview is the most underrated piece of software ever. If you spend some time with it you'll find out that you can use it to perform a lot of, sometimes less obvious, functions.

Today I'm going to talk about digital signatures. If you send documents that are (or should) be signed, you probably print them, then sign and then scan them again so they're properly signed. The thing is, it's a lot of trouble and you know that scanned docs don't look as good.

Preview has a tool that allows you to scan a signature, without even needing to have a scanner at hand as long as your Mac has a built-n iSight camera (which it probably has), and add them to your PDFs in a jiffy.

The process is really simple:

1. Write your letter or whatever it is using your favourite text processing app (just make sure you can save the document has PDF) and save it as a FDP file.

2. Make your signature with a black pen on a white paper. Make it pretty and a little bigger than usual (use a black felt pen since it works best).

3. Open it with Preview and click the Annotations icon.

4. The Annotation Bar will pop down. Click on the Signature icon.

Here you can see two options (don't mind my other signature - you probably don't have any there). Click "Create Signature from Built-in iSight".

A new window opens with a kind of scanning window that shows the image captured by your camera. Hold the paper steady and so that the signature rests on the blue line as you see below. Once you're happy with the scanned signature, click Accept (tip: use the Return (Enter) key).

Make sure you have enough light on it and hold it really steady or it won't scan properly.

Don't mind if you can't get it right on the first attempt. It took me a few trials to get it just right.

5. And that's it. You're signature is saved and you can use it to sign your docs without all the print-sign-scan hassle. All you have to do now is to click the signature icon again

and choose the signature you want and click in the place you want it in the document (you can resize it there).

And you're off to impress with your properly signed document.

-João