Federation Commander

I'm looking at buying RA or KA from E23, and I'm wondering if I buy the RA ruleset, do I need to purchase the KA rules as well?

Just bought RA, and so can answer my own question now!

There are a very small number of rules in the KA ruleset that aren't in RA.

B4 Countermeasures is not in RA, though the options index lists it as such.