RFG was a sub-brand of the manufacturers ROUSSON et CHAMOUX, based in Feurs, about 30 kms north of St Etienne.The company was better known to the cycling fraternity for manufacturing the excellent MAXICAR range of sealed-bearing hubs.
I'm not fully certain what the abbreviation stands for and Amir's explanation of Roulements Francais Garantis could be correct. It could also stand for Roulements Fiables Garantis which, loosely translated means Reliable Guaranteed Bearings - these adjectives featuring regularly in the firm's advertising descriptions.
The company was a broadly based engineering one, that had large investments in manufacturing, drive systems etc for agricultural applications. It also carried out a variety of plating operations. It ceased its cycle parts operations in the 1990s , but continued trading..and still does, having changed its name to DJ Meca in 2004. It still trades from the same address but has now diversified into new fields of manufacturing, but still carries out a lot of CNC machining.
Norris Lockley , Settle UK
(If this email reaches the CR List I will know that my computer problems of the last month or so have been resolved.)