UDIMs in Reality Converter

I have a 3d model with UDIMs that I would like to convert to USDZ but not sure if there is support in Reality Converter although the documentation implies you can load up to 6 2k files - unless I have misunderstood this...

https://developer.apple.com/documentation/arkit/adding_visual_effects_in_ar_quick_look_and_realitykit

(in the Control Texture Memory paragraph)

If this right then how do you use Reality Converter to import multiple maps into a given texture field (eg. diffuse) or are there required steps/formats when exporting from Blender

Any help would be greatly appreciated