To cite rcdk in publications use:

  Guha, R. (2007). 'Chemical Informatics Functionality in R'. Journal
  of Statistical Software 6(18)

A BibTeX entry for LaTeX users is

  @Article{,
    author = {Rajarshi Guha},
    journal = {Journal of Statistical Software},
    number = {6},
    title = {Chemical Informatics Functionality in R},
    volume = {18},
    year = {2007},
  }