Just save it as CGATS.
You don't see the option or you can't? I can on this end do both. Specifically what reference data are you trying to save?
I loaded the "Default i1i0" target, saved as .txt. Ditto for one called ETC1728RGB. Again, saved as CGATs (txt), CTP opened it fine. I tried with a custom chart I built, again, a text file CTP was able to open.