The Dutch winger hit the post on Saturday, coming closer than any other player to breaking the deadlock.
"I think we've all got mixed feelings after that," Summerville said. "We recovered from a slow start, I think we showed a lot of character in the second half, and in the end we were unlucky not to come away with the win.
"At half-time the manager (Julen Lopetegui) said we were playing like we were a bit afraid, and we weren't sure why, but in the second half we were much more like ourselves.
"We were looking for the goal, and I'm a bit frustrated with myself that I wasn't able to score. I just need to carry on working at the training ground and make sure that next time I'm in that position it finishes with a goal."
Summerville also produced a superb block to keep the clean sheet intact.
"We are a team, and I will die for the team," added Summerville. "It was a bit of a strange action, but I was determined to not let him score, and I managed to do that.
"The clean sheet is good, and we have to take the positives into the international break now and come back stronger. We know overall this season it's not been great, but there are good things and we are confident we can keep building."