I've never come that far in the game making, but I thing I should first have it seperated by writing what they do; Scripting, Eventing, Mapping etc. You could also write what parts everyone made, like
========[Mapping]============
Kyra - This and that town
Some other guy - Those castles
=======[Scripts and functions]====
Blizzard - Combat system and Online function
ForeverZer0 - Message System
And so on. If you are uploading your game on a site where most people work with Rpg maker and know about it's scripts, you can write the scripts names instead.
And in the end, you can have special thanks and such