here is a list of articles about this issue
http://www.codeproject.com/Articles/25819/The-R-Statistical-Language-and-C-NET-Foundations
http://joachimvandenbogaert.wordpress.com/2009/03/26/r-and-c-on-windows/
http://developereventlog.blogspot.de/2012/07/introduction-to-c-and-r-integration.html
http://vvella.blogspot.de/2010/08/integrate-c-net-and-r-taking-best-of.html
http://vvella.blogspot.de/2010/08/interfacing-c-net-and-r-integrating.html
http://vvella.blogspot.de/2010/08/interfacing-c-net-and-r-integrating_17.html
http://www.billbak.com/2010/11/accessing-r-from-clessons-learned/
http://psychwire.wordpress.com/2011/06/19/making-guis-using-c-and-r-with-the-help-of-r-net/
sources:
http://sunsite.univie.ac.at/rcom/
http://homepage.univie.ac.at/erich.neuwirth/php/rcomwiki/doku.php