My previous GP never prescribed me iron despite my ferritin being 38. However I have taken some over the years, although it never agreed with me very well, and it was up to 93 when checked by my new GP, who seems to be more knowledgeable about rls. In February she prescribed Ferrous Fumerate 210mg twice a day, which I took with vitamin C to help absorption, and this agrees with me well. By the end of March, after 6 weeks, my ferritin was up to 126, and now it is 219!
So this is a great response and my rls does seem to be reduced a bit, but not gone - yet. So still hoping.