Thank you Lunarea. I am able to download resources to folders as mentioned in the guide you posted, but my assumption is there must be at least one step in-between importing art into a usable format for the faces and pictures folders to accept, and that is the process that I have no knowledge of.
Faces have a preset size, you can look it up in the help file or export an existing face file from the resource manager to compare.
However, most of the artwork from concept artists is used either as busts (NOT as faces) or as battlers, and for either busts or battlers there is no specific limitation other than they need to fit on the screen, and because of that those files do not need to be processed other than a resize to the size YOU want them to be on the screen (which is defined by yourself, not by the program)
If you want a face, then stay with the artists who know how to make a face.
If you want a bust or a battler, then there is not step between, you'll either use a show picture command or a bust script (search for them on the forum) or import them as battler pictures and use them on the enemies in the database.