Howard had not featured in Reading's starting line-up for 13 games coming into this clash, but his fine cross created a first-half opener for Shane Long before he put the game beyond Doncaster with a well-taken finish 13 minutes from time.
Billy Sharp gave the home side hope with a penalty in the 80th minute - after former Rovers' defender Matt Mills was dismissed for handball - but Reading survived a late onslaught to claim back-to-back league wins for the first time this season.
"Brian was excellent," McDermott said. "And that's everyday. He has come in every day and worked really hard.
"I cannot fault his attitude. He trains hard and is a good character to have around the place. He got a chance and played superb.
"I was so pleased for him - scored one and made one. A great cross for the goal and a superb finish for his goal."
Source: PA
Source: PA