Yes, you just create the logo as its own file like you would any other image, then copy it and paste it as a new layer on what ever image you want it on. Signing with a logo looks great - so long as it's a good logo. You may also like to add your website address if you have one, or some other detail so people know how to find you if you are in the market for freelance work. On the other hand, a nice simple cursive font in your name can also look nice.