Hi Tweed,
I have 2 of the Mathews unmarked OR cap badges as well as a marked silver one.
I will attach some pics. Reuteler did manufacture RAR silver collars with various obverses, not sure about the cap badges though.
One thing I have found is that the font on the Rhodesian made cap badges differs to the Firmin ones. Also if you look carefully at the "stitching" of the shield, you will notice that the Firmin cap badge has more stitches than the locally made ones.
Dave
3 RAR OR Cap badges LH local manf & other 2 UK made.jpg