I’d never heard of that technique until now. This link on software for Ranked Set Sampling just uses a sample size formula for a pure randomly selected sample:
My intuition is that a better sample size and power analysis formula would need to know the order statistics or the extreme value distribution of the data.
I did not noticed any work on optimum selection of set sizes on unbalance ranked set sampling. If there is no work it can be an idea to carry out research for selecting optimum sizes under imbalance ranking. I have already worked on a proposal suggesting the same idea not completed yet.