Mario, I have had the same need and have done as HH has suggested, but just with not nearly so much "attention to detail" because what gets inserted tends to look like your signature in printed form anyway.
I signed my name on white paper, scanned it, cropped the resulting scanned image to just the signature, and saved it as a JPG. Then I used the now very old Microsoft Photo Editor software from WinXP (which does not have to be installed, it can be copied on to USB stick and run standalone without any problem) to set transparency to anything that is white (or even close to it) in the background and saved the result as a PNG file. MS Photo Editor has to this day what I consider to be the easiest "set transparency" feature of any digital photo editor I've ever used. This can then be included in most other files with an "Insert Picture" or "Insert Image" command. One of the tricks, though, is getting the scaling right, and I have no idea how you'd do that without being able to see what's on the page. Most often when I insert a PNG image it is much larger than it need be, in fact the signature is often much larger than the original it was scanned from. I have to grab the corner of the picture and do a diagonal "shrink" to that the width to height perspective is maintained until it's the right size for where it's going to be placed. If the process HH mentions results in a file that's scaled at 100% of real life size of your signature, and it stays that way upon insertion into an electronic documents, it's well worth taking the extra time and effort to create a file in EMF format. Brian