To cite package 'RMediation' in publications use:

Tofighi, D. & MacKinnon, D. P. (2011). RMediation: An R package for mediation analysis confidence intervals. Behavior Research Methods, 43, 692--700. <doi:10.3758/s13428-011-0076-x>

Corresponding BibTeX entry:

  @Article{,
    title = {RMediation: An R package for mediation analysis confidence
      intervals},
    author = {Davood Tofighi and David P. MacKinnon},
    journal = {Behavior Research Methods},
    year = {2011},
    volume = {43},
    pages = {692--700},
  }