If you are running an older version of Telerik Reporting, and it only gives you the option for VS 2008 and VS 2010, it is because at the time we released that version of the product, the latest available official version of VS was 2010. We always aim to add support to the product as soon as a new version of VS is released.
A possible approach is to have different versions of Visual Studio installed side-by-side as elaborated in the Installing Visual Studio Versions Side-by-Side
article. Then you can create/modify your projects with the supported version of Visual Studio, and if needed, upgrade the projects later to a newer version. Or you can get the latest version of Telerik Reporting, which supports Microsoft Visual Studio 2010, 2012, 2013 (Professional, Premium and Ultimate Editions).
Let us know if we can be of any further help.
New HTML5/JS REPORT VIEWER with MOBILE AND TOUCH SUPPORT available in Telerik Reporting Q3 2013! Get the new Reporting version from your account or download a trial.