To cite package 'RSA' in publications use:

Schönbrodt FD, Humberg S (2020). RSA: An R package for response surface analysis (version 0.10.1). https://cran.r-project.org/package=RSA.

Corresponding BibTeX entry:

  @Manual{,
    title = {{RSA}: An R package for response surface analysis (version
      0.10.1)},
    author = {Felix D. Schönbrodt and Sarah Humberg},
    year = {2020},
    url = {https://cran.r-project.org/package=RSA},
  }