Jim,
I love a good search and finding out about different firearms but this one didn't turn up much as you already found out. Nevertheless, here's what I found - hope it helps:
Sometimes they were called "RAF model SIDNA" other sites referred to them as "RAF-Sidna" and they were also produced under the license name "Reina". This seems to be the address of the factory, which I think is now closed:
"Etablissements RAF, 103, rue Antoine DURAFOUR, 42100, Saint-Etienne".
Another rifle that sold in France:
http://www.theauctionadvertiser.com/DLa ... 101127.pdf
Date: 11/27/2010 Location: PARIS FAIRGROUNDS
RAF MODEL SIDNA OVER / UNDER 410 X 3"/ 22LR, 610MM BARREL, SER #2862
Perhaps if you can read French (best I can do is "mercy buckets") you could do a Google search in French... that might help?
If you get it, we've got to see pics and get all the details!
Best of luck on it.
Though defensive violence will always be “a sad necessity” in the eyes of men of principle, it would be still more unfortunate if wrongdoers should dominate just men. - St. Augustine