I'm not sure how to find per game +/-, but EvanMiya tracks it for the entire season:
EvanMiya Player Ratings. Select A10 in the conference field and then Richmond in the team field. I don't think this counts the Southern VA game, though.
Sports Reference also tracks Box Plus Minus which is a more advanced version that takes into account your entire box score contributions instead of just the score differential when you're on the floor. See the "BPM" column here:
Sports Reference Richmond Advanced Stats.
Per the above link, -1. He's #5 on the team in BPM though, only behind Argabright, Beagle, Thomas, and Daughtry.