hmm.. I have been working with reindeer skin for some time, bu I have never ever backed a bow with any type of skin. I guess it should do fine, but no miracles to be expected. If I were you I would do something else from them hides
I can not help my self, but Sami people don't only live in Scandinavia. I think Fennoscandia would be more of a geographically correct term. Good luck With the hides!