Struggling with a Mod


Club Supporter
I use Frosty Editor & Frosty Mod Manager and have no difficulty importing mods with this suite. Importing Coeff,Colour& normal images is easy and straightforward.
I am however really struggling to import some Puma boots that don’t have coeff/colour/normal images but have a png/rx3/rx3texture instead.
The png image (which I assume is the colour image) imports straight away) but the rx3 & rx3texture images won’t import.
Would I be correct in assuming that the rx3 is normal and the rx3texture is the coeff?
If anyone could assist on how I can import the rx3/rx3texture images I would be extremely grateful. Thank you