Before we get into keying, we need to talk about Rolemaster itself.
There are two products for Rolemaster. Rolemaster Classic, and Rolemaster the Standard System/Fantasy Roleplaying. I want you to know -- both have their strengths and weaknesses.
Rolemaster Classic is the original Rolemaster system. With all of it's associated problems: profession creep, and a large amount of rules in each of the Companions its silly. But the rules are optional. All you really need for Rolemaster Classic are Character Law, Arms Law, and Spell Law. The pictures are found below of each of these books. If you are the GM, Creatures and Treasures comes in stark reality.
It is going to be the system of use for this series because the original system is simpler and it is easier to generate NPCs for it. Only the first three books are going to be used -- Character Law (and Campaign Law), Arms Law (2003 Edition), and Spell Law.
Rolemaster Fantasy Roleplaying (or the Standard System) is a more advanced system where you need just the basic professions, but you use training packages to produce your characters. There are many sourcebooks for RMFRP, all of which are either available from ICE, your local game store, and the web.
Three products transfer from RMFRP directly into Classic easily. Parts of Character Law (RMFRP version), Arms Law, and the Armory (with it's famous table for throwing gnomish -- or halfling -- henchmen). Rest assured, though, the Stat Blocs in Classic are easy.