RGF is Raccord Gargette Freres. As Richard points out French lug makers. I
havnt come across any other components or equipment from them. They have
been around since the 1950's. I have a 1956 Ephgrave with RGF in the oval
stamped on the bracket. Your frame could be earlier than 70's to me,
possibly a 50's Road Path frame. Is the brake bridge drilled for brakes?
Fiamme red label rims are also from that period.
Hope this helps. Mark Stevens in cloudless but cold Dingwall.Scotland.