Which field of the metadata?
If in the source, origin or copyright, (or other places that aren't read by the stock sites) no problem. If in the description, or keywords, I think there will be a problem.
After that, everything else Jo Ann wrote holds. They strip it off anyway. But I have it there, in case some other time I want to send a file out, so it's on everything. I also have my name in the camera data, for every camera I own.
In an old discussion I noticed it was suggested to put name, copright, url in metadata. You can put your personal URL in the metadata and shutterstock will accept it?