To cite package ‘aftables’ in publications use:

  Dray M (2021). _aftables: Generate spreadsheet publications that
  follow best practice guidance from the UK government's Analysis
  Function_. <https://github.com/best-practice-and-impact/aftables>.

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {aftables: Generate spreadsheet publications that follow best practice guidance from the UK government's Analysis Function},
    author = {Matt Dray},
    year = {2021},
    url = {https://github.com/best-practice-and-impact/aftables},
  }