The first question would be like: Can he create Rasen-Shuriken in kyuubi form? BECAUSE, when Naruto created FRS he threw it in air, since he was in sage mode he controlled nature energy hence he could controlled even after throwing it in air. But Kyuubi form isn't like that .. chakra comes from inside of him not from outer nature.
If I am not wrong.. beast chakra is like natural energy. So recalling Naruto's sage technique! It is just a free form energy which he could mould as 'rasengan + Wind nature chakra' creating a rasen-shuriken! But adding his wind chakra to create maximum of 2 rasen-shurikens used to bring his Sage mode to an end.
Now if he is granted with unlimited chakra from Kyuubi, the 9-tails .. can he build unlimited number of rasen-shuriken?