There are many ways to put a signature or logo on a photo. You might want to create a Photoshop Action to put a conspicuous signature on your proofs. Then you can create a Droplet which calls (uses) that action. Then you can drag a whole folder of images into the Droplet and the action will work on all of the images. Suggestion: have your action make a low resolution COPY of your image, put the signature on it, then Save it to a special folder.

My preferred way to sign a print or put a copyright notice on it is to first create the type or logo in a neutral gray and size it to fit where I want it (on its own layer)... I place it along a line in the photo, maybe in a shadow. Then I change the Blending Mode of the signature layer to Overlay. It'll look as if it has disappeared! Then I put a bevel (fx) on the layer and the signatue/logo shows up as if it's embossed on the photo. Very subtle.
Hope this helps I copied it from another website that I sometime use. Also if you go to Action Central Website there are a few FREE actions that can be downloaded