I have had a look at the censuses and agree with you. I can't find any in Gleneagles or even Auchterarder. There are, however, quite a few in Perth and one, slightly nearer, in Forgandenny..... but I know that there were Proudfoots in Perth quite a way back (I think I saw some on the 1851 or 1861 census) so could you be linked to those and they've moved out??
If I can help you with this, I live local to the area.
Best wishes
Possum