Transforming Rc band data

I've been formatting my photometry spreadsheets to fully transform my differential B,V,Rc,Ic photometry onto the standard system. Using Gordon Sarty's useful paper, I was able to do this for B,V and Ic. I'm a little unsure about how to handle the Rc data. Some years ago, Arne recommended determining Tr vs. V-Ic instead of V-Rc. So when I calculated my Tr coefficient, I did it vs. V-Ic. In Gordon's paper, he shows examples of R mags transformed using Tvr or Tri, but not Tvi. How do I transform my Rc data using Tvi? Do I still need Tvr to first calculate the standard color or can I use Tvi for the Rc data? Thanks, Bob