[R-meta] How to define Rosenthal & Rubin's Proportion Index?

[Patrizio Tressoldi]

I'm using the Rosenthal & Rubin's Proportion Index as a measure of
effect size (Rosenthal, R., & Rubin, D. B. (1989). Effect size
estimation for one-sample multiple-choice-type data: Design, analysis,
and meta-analysis. Psychological Bulletin, 106(2), 332-337).

The range is 0-1, with the null effect = .50.

How can I define this particular ES with a rma analysis?

Thank you

Patrizio