Guthrie was disciplined by the club after refusing to travel with the Royals squad for their game with Sunderland on 11 December.
"I do feel I've got a point to prove. Obviously, it's been a difficult few weeks," he told the club's official website.
"I worked my socks off and I'll only get better. It was a really good starting point for me.
"It was nice for the fans to give me their backing. I noticed that at (the 1-0 defeat at) Man City when I came on they were behind me and being at home it was nice.
"I want to kick on from here. They had a right to (jeer at me) and I was prepared for that. But it was a nice boost before the game."