Me too, same as bobander.
I bought these common thick 1" round felt pads, the kind you place on the bottom of chairs to slide on wood floors. I stuck them to the bottom of the 4 antenna feet and also on the antenna wing tips. That horrible rattle is now 100% gone.
I did trim the wing tip pads into strips. Given the roof has a slope, make sure the wing tip pads make "first-contact".