To cite rddapp in publications use:

Ze Jin, Wang Liao, Irena Papst, Wenyu Zhang, Kimberly Hochstedler, Felix Thoemmes (2021). rddapp: Regression Discontinuity Design Application. R package version 1.3.2.

Corresponding BibTeX entry:

    title = {rddapp: Regression Discontinuity Design Application},
    author = {{Ze Jin} and {Wang Liao} and {Irena Papst} and {Wenyu
      Zhang} and {Kimberly Hochstedler} and {Felix Thoemmes}},
    year = {2021},
    note = {R package version 1.3.2},