Royals robbery irritates McDermott
Goals to Robert Huth and Cameron Jerome established a two-goal buffer for Stoke before Adrian Mariappa reduced the deficit with seven minutes to go.
As the Royals were desperately seeking an equaliser in stoppage time, striker Adam Le Fondre went down in the box under pressure from Ryan Shotton but claims for a penalty were dismissed by referee Michael Oliver.
"Once we got to 2-1, I thought we would get it (a draw), and unfortunately the ref has missed a penalty at the end, the last kick of the game," McDermott said.
"He got hold of the ball, flicked it by him and he caught him. It was a stonewall penalty. I've just gone in to see him (Oliver) and he didn't see it that way, so that's fine, but I thought it was.
"Sometimes as a manager you get those things - with the last kick of the game, it would have been great to get the point. We hung in there and showed great resilience and desire. This is not an easy place to come to, which everyone knows."
Stoke boss Tony Pulis was relieved the late penalty wasn't awarded and said it wasn't clear if Oliver made the right decision.
"Firstly I was told it was a penalty, then I've just been told it actually isn't from a different angle - that the lad isn't caught, but just arches his back and falls over," Pulis said.
"It will be interesting to see, but if it was a penalty, I have to say thank goodness we have had a break, because we deserve one."
Pulis believed his side's first win of 2013 was just reward, praising the impact of his bench in the second-half.
"It has been a long time. I thought we deserved to win the game - I would have been absolutely devastated if we hadn't won the game today," he said.
"After the first half I thought we deserved to be coming in leading, but we just picked the pace up and the two subs (Jerome and Kenwyne Jones) made a great difference again.
"Cameron Jerome is a great impact player and he scored a great goal."
Next weekend, Stoke face a tough trip to Fulham while Reading host Wigan as they bid to avoid sinking into the relegation zone.