RGF was indeed a FR maker of frame bits, best known for their BB shells but they made them in at least 2 (maybe more) threadings and they were very popular with Brit builders. Would not be out of the question for this to have been built in nearly any country in Europe....but can be narrowed down with some critical clues: what are the ODs of the 3 main tubes? What is the BB threading (looks like maybe a Stronglight BB unit? The seat cluster is very interesting, both being a shot-in fastback" but also the "Dutch style binder" yet this is opposite (male bolt head on the LEFT instead of Right) to common practice.
What are those "caps" on the WB bosses?
What dropouts and fork end brand?
Take a pic of the bottom of the BB shell.