The Cottagers are without a win in their last six Premier League games and still not mathematically safe from avoiding the drop.
Rodallega, who came on in the 27th minute, admitted that he feels bad about the poor result, but urged his teammates to get their heads up for the upcoming clash against Liverpool.
"The game was a little complicated as we were 1-0 down early, which was a bit of a surprise for us," Rodallega told the club's official website.
"I was happy with the way I played when I came on. I feel bad that we lost the game and the boys are very down, but we must keep our heads up for the next match against Liverpool as they are a big team and we need the three points."
Rodallega has made 28 Premier League appearances for Fulham so far this season.