To cite the psych package in publications use:

Revelle, W. (2016) psych: Procedures for Personality and Psychological Research, Northwestern University, Evanston, Illinois, USA, https://CRAN.R-project.org/package=psych Version = 1.6.9.

Corresponding BibTeX entry:

  @Manual{,
    title = {psych: Procedures for Psychological, Psychometric, and
      Personality Research},
    author = {William Revelle},
    organization = { Northwestern University},
    address = { Evanston, Illinois},
    year = {2016},
    note = {R package version 1.6.9},
    url = {https://CRAN.R-project.org/package=psych},
  }