Power analysis for relative risk equivalent to power analysis for difference between two proportions?

I need to make a power analysis calculation to estimate the minimum sample size for a relative risk statistic (ratio of two proportions) for unmatched data - two independent samples.

Can I use the power calculations in the R pwr package for testing the difference between two proportions? Or will this return inaccurate sample size estimates?

EDIT: I see there's a power.cmh.test option in the samplesizeCMH package that allows you to find power and sample size for Cochran-Mantel-Haenszel tests. Can I apply this to any relative risk statistic, even if it's not a case-control study?

The relative risk, $$RR$$, is simply $$RR = \pi_1/\pi_2$$ for group probabilities $$\pi_i$$. This means that $$\pi_1 = RR \pi_2$$.
Thus, a power analysis to detect a relative risk of $$RR$$ is equivalent to a power analysis to detect a risk difference between $$\pi_1$$ and $$RR \pi_2$$. See chapter 3 in Biostatistical Methods 2e by John Lachin for more.