Hi dana,
I find the worst "squeaking" rubber sole offenders are the kind (like on moccasins or boat shoes, for example) that have those very fine, almost razor thin cuts in the tread design. They're great walking over ice in the winter, but they squeak on piano pedals. Tire companies use that same process on winter tire treads. The manufacturing process has a specific name, but I can't recall it at the moment.
Joseph Banowitz, author of The Pianist's Guide to Pedaling, is probably the foremost expert. He states that the pressure point between the foot and the pedal should be at the junction of the foot and toes. But everyone is slightly different. Horowitz though used to lay the outside edge of his right shoe on the floor with the inside edge touching the damper pedal. Then, instead of depressing the pedal as you or I might, he would then apply pressure from the inside edge of the shoe down along the right-most edge of the damper pedal. So he actually operated the pedal from the side of it instead of front-on from the top!