As a Roblox developer, currently it’s too hard to set which rig the player uses. You have to store blank R6/R15 characters and then load the character appearance into it, which shouldn’t have to be done.
If rigToLoad (HumanoidRigType) is unspecified, default behavior.
Otherwise, will load the specified rig (R6/R15)
This makes it easy to force-load the rig you want, if you need to switch between R6/R15.