Of course. Many blind people use something called a signature guide, which is usually a small piece of metal, cardboard, or plastic, with a horizontal slot cut into it. A sighted person places the guide on the paper that a blind person needs to sign, and it helps keep the signature straight. One may also ask, how would a blind person learn to write? You can either, hold a pen and have someone help you write it a couple of times until you learn how to shape each letter, or you can just look at a large, raised version of the letters in your name and figure it out from there. It's pretty simple. Try writing your name with your eyes shut a time or two and you should get a pretty good idea of how it's done.