I thought all RSX cranks that Shimano made were with a 110mm bolt circle, and 74mm for the granny on the triple cranks. While a 130mm bolt-circle can handle a 48/38 combo (38t is the smallest possible ring for 130mm BCD), I think every triple I've seen with 48/38 as the two large rings has been a 110mm bolt-circle.

As an aside, one thing that interests me is why the compact double didn't catch on when Shimano introduced it with RSX in the 1990's. Maybe because they marketed the double with a 46/36 chainring combination, which doesn't have the wide-gear-range benefits that makes the compact double so desirable. Or maybe just because they introduced it in a low-end component group (RSX was replaced by Sora in Shimano's road-components lineup).
My dad's mid-90's Trek is equipped with RSX with a 46/36 double crank.