This is what these sprites will look like at 2x scale on a 48x48 tileset! I'm not sure if RPG Maker MV will let you scale the sprite size in the program or not. Look for an option to do that. If not, you can take the sprites into an image editor and scale the image/sprite size there!
RPG Maker is next up on our list and we will be making a guide and possible plugin for easily adding our sprites. Let us know if you have any other issues!