Harris was outstanding in victory over Colchester.
He came off the bench to seal victory late on when he headed home Clayton Donaldson's cross.
"You can see Kadeem gave us another option," Rosler said. "When you have someone with pace running at people you don't always need the full-back overlapping.
"We kept him wide and wanted to keep feeding him the ball.
"He gives us pace and that is what we've looked for since Conor [McAleny] unfortunately broke his leg.
"I am very happy to have him. We can see he is very young and has a lot of work to do but very happy and thankful that Mark [Warburton] got me the player.
"I think he will enjoy his loan spell and I think he will get a lot of playing time - he won't always start."
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