In follow-up to resolve my issue with mounting a Shield RMSc to my Springfield Hellcat Pro I talked to Springfield Customer Service and they thought it should fit. Shields website indicates an RMSc will fit a Hellcat but is not specific to models. Shield does have a video out showing the RMSc being mounted to a Hellcat OSP which Springfield Customer Service indicates has the exact same cut/footprint as the Hellcat Pro. Springfield recommended I take the site to a gun smith who could fit it for me. Not wanting to spend the money on a gun smith and not wanting to wrench the site I used a razor knife and removed a little of the aluminum from the site bottom and it now fits fine. I removed less than a 1/32 of material from the two rear mounting indentations on the bottom of the site.
Now I don't know which manufacturers Spec is off, but I shouldn't need to do that to make the site fit. Hopefully everything will work as intended and i will be happy with the site.
I was trying to upload a couple of pictures but the site indicated they were to large.