RNS is a code written by Nikolaos Stergioulas which constructs models of rapidly rotating, relativistic, compact stars using tabulated equations of state which are supplied by the user. Please direct questions about this program to either Sharon Morsink or Nikolaos Stergioulas.
The code was mainly developed while Stergioulas and Morsink worked at UWM, Nikolaos as a graduate student and Sharon as a postdoc. Currently Nikolaos Stergioulas is an assistant professor at the Aristotle University of Thessaloniki (Greece) and Sharon Morsink is an Associate Professor at University of Alberta (Canada).
The code is based on the method developed by Komatsu, Eriguchi & Hachisu (1989) and modifications introduced by Cook, Shapiro & Teukolsky (1994). It can compute individual models as well as sequences of fixed mass, rest mass, angular velocity or angular momentum models. All models assume uniform rotation. You can read more about this code in Stergioulas and Friedman (1995) and in Nozawa, Stergioulas, Gourgoulhon & Eriguchi (1998) and references therein.
A list of publications which use the rns code is available.