What could you include to give a sense of scale in a photograph of a mountain?

Well are you taking the picture because if you are then you should try moving the camera to where you are looking at the mountain on like a side like picture a graph and pic a side of the graph and take the picture that way but if you are editing the picture try to make the picture pop! hope that helps btw I might be wrong but hey at least you go a answer out of somone! XD

Well, if this is for photography you can angel the camera in specific angles that gives it more depth, and if you want, use enhancements to do this further. This will make it appear more deep and angular, as well as give it a scale.

Monophony.  hope this ! : )