As a general rule in most species the female will have shorter pectines with less teeth on each comb than males of the same species; but of course you would need several to make that determination. There are ID keys around that list the average number of pectines for males and females in many species. However, I'm not up in that area of the literature.
Might want to see if you can get Dave Gaban who frequents the yahoo group ScorpFans or Chad Lee who sometimes can be found here as well as on ScorpFans. One of them should be able to point you in the right direction for ID keys of N american scorps.