To cite package 'geomorph' in a publication use the first two
references.  If analyses with RRPP were used, cite the four references:

  Baken E, Collyer M, Kaliontzopoulou A, Adams D (2021). “geomorph v4.0
  and gmShiny: enhanced analytics and a new graphical interface for a
  comprehensive morphometric experience.” _Methods in Ecology and
  Evolution_, *12*, 2355-2363.

A BibTeX entry for LaTeX users is

  @Article{,
    title = {geomorph v4.0 and gmShiny: enhanced analytics and a new graphical interface for a comprehensive morphometric experience.},
    author = {E. K. Baken and M. L. Collyer and A. Kaliontzopoulou and D. C. Adams},
    year = {2021},
    journal = {Methods in Ecology and Evolution},
    volume = {12},
    pages = {2355-2363},
  }

  Adams D, Collyer M, Kaliontzopoulou A, Baken E (2024). “Geomorph:
  Software for geometric morphometric analyses. R package version
  4.0.8.” <https://cran.r-project.org/package=geomorph>.

A BibTeX entry for LaTeX users is

  @Misc{,
    title = {Geomorph: Software for geometric morphometric analyses. R package version 4.0.8},
    author = {D. C. Adams and M. L. Collyer and A. Kaliontzopoulou and E. K. Baken},
    year = {2024},
    url = {https://cran.r-project.org/package=geomorph},
  }

  Collyer M, Adams D (2024). “RRPP: Linear Model Evaluation with
  Randomized Residuals in a Permutation Procedure, R package version
  2.0.3.” <https://cran.r-project.org/package=RRPP>.

A BibTeX entry for LaTeX users is

  @Misc{,
    title = {{RRPP}: Linear Model Evaluation with Randomized Residuals in a Permutation Procedure, R package version 2.0.3.},
    author = {M. L. Collyer and D. C. Adams},
    year = {2024},
    url = {https://cran.r-project.org/package=RRPP},
  }

  Collyer M, Adams D (2018). “RRPP: An R package for fitting linear
  models to high‐dimensional data using residual randomization.”

A BibTeX entry for LaTeX users is

  @Misc{,
    title = {{RRPP}: An R package for fitting linear models to high‐dimensional data using residual randomization.},
    author = {M. L. Collyer and D. C. Adams},
    year = {2018},
    journal = {Methods in Ecology and Evolution},
    volume = {9},
    issue = {2},
    pages = {1772-1779},
  }

As geomorph is evolving quickly, you may want to cite also its version
number (found with 'library(help = geomorph)').  Additionally, the RRPP
package should also be cited for any analyses using RRPP. (See
'library(help = RRPP)' or 'citation('RRPP')'.)