To cite package ‘Rfast’ in publications use:

  Manos Papadakis, Michail Tsagris, Stefanos Fafalios (2023). _Rfast: A
  Collection of Efficient and Extremely Fast R Functions_. R package
  version 2.1.0, <https://github.com/rfastofficial/rfast>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {Rfast: A Collection of Efficient and Extremely Fast R Functions},
    author = {{Manos Papadakis} and {Michail Tsagris} and {Stefanos Fafalios}},
    year = {2023},
    note = {R package version 2.1.0},
    url = {https://github.com/rfastofficial/rfast},
  }