With K2 alone it now works however with K2+SE AAI Industry which is required is overriding the changes. I already made a post about this on Slasherbane's compatibility mod. I don't use the RTG mod as SE has it's own.
Also would it be possible to dynamically make it so other mod that has K2 as a dependency for fusion and antimatter cells be able to use the RFP cells. I use a few of these as well. The one I have are Insectitronics, Spidertron Extended (which also overrides the changes for the regular spidertron), and Krastorio 2 - Additional Locomotives (this one also needs antimater cells).
Thanks for making this work with K2.