Hello Robert and welcome to the ArtRage forums.
I must confess I'm not entirely sure what you are trying to do there…
But some things to bear in mind with AR files.
An ArtRage .ptg file can only be read/edited by ArtRage, so if you are wanting to open your AR files in Photoshop to work on them there, still with all their layers in place, then you will need to export copies of them from AR as .psd files for Photoshop to work with.
Also AR keeps track of paint wetness, thickness etc… which Photoshop will not be able to work with so this information will be lost in Photoshop.
If you are planning on moving the same painting to and fro you may want to turn off AR's canvas lighting before each new export as the effect can start to build up. However if you turn the light off then things like oil brush marks won't show up and the painting may look "flat"…!
When bringing a .psd file back into AR any areas of paint will be given a default wetness and depth which may not be exactly as it was when first created in AR.
I would strongly suggest you make some experimental paintings in AR and get a feel for how each app handles them when passing them back and forth.
Maker Of Replica Macoys
Techie Stuff:
ArtRage 5.0.5 ~ 15" Macbook Pro + 22" HD Monitor ~ macOS 10.12.6 ~ 4 Core i7 3.1GHz CPU ~ 16GB RAM ~ Wacom Intuos4 M and a Spyder4Pro (to keep the colours true!)