To cite package ‘ratematrix’ in publications use:

  Caetano D, Harmon L (2022). _ratematrix: Bayesian Estimation of the
  Evolutionary Rate Matrix_. R package version 1.2.4,
  <https://CRAN.R-project.org/package=ratematrix>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {ratematrix: Bayesian Estimation of the Evolutionary Rate Matrix},
    author = {Daniel Caetano and Luke Harmon},
    year = {2022},
    note = {R package version 1.2.4},
    url = {https://CRAN.R-project.org/package=ratematrix},
  }