Aug. 30—NORMAN — While receiver Marvin Mims figures to be the Sooners’ primary punt returner after handling those duties a year ago, with Drake Stoops backing him up, there’s much more uncertainty as to who will handle the kick return duties. “I’m not sure we won’t try a few guys once we get into the season,” OU coach Lincoln Riley said. “It’s a little bit of a tough one to simulate. Most of the…