The 20-year-old striker, who can also play on the wing, has signed from Scunthorpe until January after finding first-team chances hard to come by at Glanford Park.
"Bobby's a player we've admired for quite a while. He's been involved for Scunthorpe this season, albeit mainly off the bench.
"It's not one I'd expect to be able to make permanent, because he's highly regarded at Scunthorpe.
"They've let him come to us because he's not getting much football and he wants to play. Bobby can play up front or in a wide role off Chris O'Grady, so he offers versatility to go with his attacking threat.
"I'm hoping he can help us improve our ability to turn possession into victories. I've been pleased with the performances, and I'm looking for the results to go with them."