To cite rotl in publications use:

Michonneau, F., Brown, J. W. and Winter, D. J. (2016), rotl: an R package to interact with the Open Tree of Life data. Methods in Ecology and Evolution. 7(12):1476-1481.<doi:10.1111/2041-210X.12593>

You should also cite the source data from the Open Tree of Life

OpenTree et al. Open Tree of Life Synthetic Tree. <doi:0.5281/zenodo.39377411>

Corresponding BibTeX entries:

  @Article{,
    title = {{rotl}: an R package to interact with the Open Tree of
      Life data},
    author = {Francois Michonneau and Joseph W. Brown and David J.
      Winter},
    journal = {Methods in Ecology and Evolution},
    year = {2016},
    volume = {7},
    number = {12},
    pages = {1476-1481},
    doi = {10.1111/2041-210X.12593},
  }

  @Misc{,
    title = {Open Tree of Life Synthetic Tree},
    author = {{OpenTreeOfLife} and Benjamin Redelings and Luna Luisa
      Sanchez Reyes and Karen A. Cranston and Jim Allman and Mark T.
      Holder and Emily Jane McTavish},
    year = {2019},
    version = {12.3},
    publisher = {Zenodo},
    doi = {10.5281/zenodo.3937741},
    url = {https://doi.org/10.5281/zenodo.3937741},
  }