McDermott celebrated his "best moment in football" as the Royals sealed promotion to the Barclays Premier League with a 1-0 win over Nottingham Forest.
McDermott praised Roberts, saying: "Jason has been crucial to us but we were doing well before he arrived.
"I have been lucky with my players and staff. They have carried me on.
"We have had difficult times and had to sell our best players but now it will be a good summer.
"The players will have tomorrow off but then it's back into training for the next game."