A friend of mine who has recently switched from analog to that other medium signs all his prints with a type of marker or pen that lays gold or silver looking ink? He signs his stylized initials (a sort of logo) in the lower right of the print itself, but very small and unobtrusive, unless you look for it in the corner. It seems from reading the above, this is probably not one of the more desirable ways, but in looking at his pics I didn't think the signature detracted from the image, but I'd never given much thought to signing photos.
I had only ever signed them lightly on the back with pencil, and near and edge so it would be where the print border is if on the front. Or I sign the back of the backer board, but that ends up under the paper dust cover.
For my working prints in RC paper I use a Sharpie and mark relevant exposure info and so forth along the bottom edge of the back, so if I do hinge mount them for my own use, I still have the info. I used to keep notes in a notebook on every print (I still do about film development), but after hundreds of prints, find it easier to simply refer to the actual working pic and the data on the back. I don't do complicated dodge and burns (minor as needed), but any of that is briefly noted on back as well. I've only been doing the Sharpie on the back for about a year, but never had any sort of issues on the RC paper. I wouldn't do it for a print I meant to sell, or on FB of course. Sri for the bit of thread drift.