To cite okapi in publications use:

  Ernest Guevarra (2023). okapi: Open Data Kit (ODK)-based
  Computer-assisted Personal Interview (CAPI) Tools R package version
  0.1.0.9000 URL https://rapidsurveys.io/okapi/

A BibTeX entry for LaTeX users is

  @Manual{,
    title = {okapi: Open Data Kit (ODK)-based Computer-assisted Personal Interview (CAPI) Tools},
    author = {{Ernest Guevarra}},
    year = {2023},
    note = {R package version 0.1.0.9000},
    url = {https://rapidsurveys.io/okapi/},
  }