To broaden it out a little. There have been two IA farmsteads excavated in my patch that may have incorportated a cup marked stone into the entrance.
Perhaps the IA equivalent of a lucky horseshoe or a bough of rowan.
I like the idea that the line between ritual and utilitarian can be blurred. There's at least one example of cup stone in a house up here in Northumberland (not sure of the date), which implies some kind of crossover, whereby the ritual is (literally) at home in a domestic context.
Of course that's assuming that RA has some kind of 'ritual' significance.