To cite package ‘xmpdf’ in publications use:

  Davis T (2024). _xmpdf: Edit 'XMP' Metadata and 'PDF' Bookmarks and
  Documentation Info_. R package version 0.2.1,
  <https://github.com/trevorld/r-xmpdf>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {xmpdf: Edit 'XMP' Metadata and 'PDF' Bookmarks and Documentation Info},
    author = {Trevor L Davis},
    year = {2024},
    note = {R package version 0.2.1},
    url = {https://github.com/trevorld/r-xmpdf},
  }