I’m not sure why it’d be giving you the “undefined method ‘include’” but the proper include is:
without the quotes. It’s not including a file but in fact telling Rails to mixin the methods of the module Magick [in the RMagick library]. I’d recommend mixing these methods in only in whatever specific class you plan on implementing RMagick in.
Also, I tried out the quotes around Magick in the include and got a different error than the one you’re talking about. I got “wrong argument type String (expected Module) (TypeError)”, which makes sense because of the reason I said above.
Hope all that helped.