The pilot of the tailwheel-equipped airplane reported that during the landing roll the airplane decelerated and began drifting to the right. He added that he applied left rudder, but the airplane continued to the right, so he added more left rudder. The airplane ground looped to the left, the right main landing gear collapsed, and the right wing impacted the ground. The airplane sustained substantial damage to the to the right aileron and empennage. The pilot reported that there were no preaccident mechanical failures or malfunctions with the airplane that would have precluded normal operation. The pilot reported that the initial lack of rudder response was due to the placement of his feet on the rudder pedals. His feet were too high on the pedal "causing the toe brakes to inadvertently be engaged during landing".