Upload & Sell: Off
fwiw, having copyright info. in the raw file instead of jpg helps when proof of ownership comes to that point since the raw file, as far as I can see and as far as these responses show, cannot be added after the fact, at least not by normal means.
If exiftool is not considered as "normal tool" then there are not many options (most graphical inteface EXIF editors base their operation to exiftool...). In my "world" exiftool is real tool, same as commercial stuff from Adobe, Apple, Phase One whatever company etc.
If you don't worry "normal tools" and other less important things, you can build workflow in which your RAW-file EXIF contains copyright info. Mine contains in addition lens, filter(s), used aperture (even lens is fully mechanical, thou it depends do I anymore remember when I import photo to computer, or if I made notes, or can determine it from other factors) and GPS coordinates.