The blessing and curse with using Game Maker for RPG's is it's a general game engine. It can has been used for LOTS of RPGs, but it doesn't specialized in it. I recommend checking out the yoyogame's marketplace section for rpg templates HERE. That link takes you directly to the RPG assets. If you download the free ones and open them up you should be able to see how different parts of an RPG can be built with Game Maker including any relevant advanced features you would want to know about.
Personally, for my own RPGs I'm using a specialized game creator, but Game Maker is absolutely solid if you take the time to learn how to code for RPGs.