Ha! My co-worker made one of these for the same reason. Some places still require "wet" signatures, and some people (us) like to stick it to bureaucracy and prove that they can't tell the difference.
For a one-liner, if you use any tool to generate a realistic version of your signature, or do what I do and actually scan a version of your signature once, and then have that as a PNG that you can drop on any PDF of your liking, here's a line to make it look nice and "scanned":
Yep, it just uses ImageMagick's `convert` to take the PDF, rotate it a little bit, blur the text, and generally reduce the quality just like a scan would.
The OP also uses a few other flags like `+noise Gaussian` and `-attenuate 0.25` which you could toss in. Same concept, just wanted to share a one-liner you can use if you already have a PDF with a signature on it, and you need that nice "scanned" look.
For a one-liner, if you use any tool to generate a realistic version of your signature, or do what I do and actually scan a version of your signature once, and then have that as a PNG that you can drop on any PDF of your liking, here's a line to make it look nice and "scanned":
Or for even more noise and poor quality: