you only play 2 classes at a time. with K/R/S you can play:
K/R
K/S
S/R
S/K
R/K
R/S
so the elite combination is primary/secondary and you can look em up here:
http://www.runesdatabase.com/ under skills
and you have to get the elites till 45 individually for S K and R side then the 50/50 for the combinations ignoring primary/secondary i think so s/r k/r k/s OR their mirror images to get em for both.