To cite RProtoBuf in publications use:

  Dirk Eddelbuettel, Murray Stokely, Jeroen Ooms (2016). RProtoBuf:
  Efficient Cross-Language Data Serialization in R. Journal of
  Statistical Software, 71(2), 1-24. doi:10.18637/jss.v071.i02

A BibTeX entry for LaTeX users is

  @Article{,
    title = {{RProtoBuf}: Efficient Cross-Language Data Serialization in {R}},
    author = {Dirk Eddelbuettel and Murray Stokely and Jeroen Ooms},
    journal = {Journal of Statistical Software},
    year = {2016},
    volume = {71},
    number = {2},
    pages = {1--24},
    doi = {10.18637/jss.v071.i02},
  }