To cite package ‘FKF’ in publications use:

  Luethi D, Erb P, Otziger S, McDonald D, Smith P (2024). _FKF: Fast
  Kalman Filter_. R package version 0.2.6, ,
  <https://github.com/waternumbers/fkf>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {FKF: Fast Kalman Filter},
    author = {David Luethi and Philipp Erb and Simon Otziger and Daniel McDonald and Paul Smith},
    year = {2024},
    note = {R package version 0.2.6, 
},
    url = {https://github.com/waternumbers/fkf},
  }