To cite metapower in publications use:

Griffin JW (2020). metapoweR: an R package for computing meta-analytic statistical power. R package version 0.2.1, https://CRAN.R-project.org/package=metapower.

Corresponding BibTeX entry:

  @Manual{,
    title = {metapoweR: an R package for computing meta-analytic
      statistical power},
    author = {Jason W. Griffin},
    year = {2020},
    note = {R package version 0.2.1},
    url = {https://CRAN.R-project.org/package=metapower},
  }