I have no experience with the DIY Truck bed liner kits, but this could work for your need. Not sure how well it would match the rhino lining. Definitely worth a shot, especially if you were able to find a pint can instead of the whole kit.
The professional products used by dealers aren't like what available for end users. Herculiner or Duplicolor have something close, so it would depend on how particular you are. Myself, the only option would be to have it patched by a rhino dealer.