Yes, you need to make sure that you have all necessary assemblies in the GAC or in the bin folder of your SharePoint web application:
- Telerik.Charting.dll - especially if you are using the Charting control
- Telerik.Web.UI.dll - this single dll is needed for all the controls in the Web.UI suite.
- Telerik.Web.Design - needed for working with DesignTime of controls. Note that this is now merged into the latest version of the Telerik.Web.UI dll release so you basically need the first two above.
I believe this will help you get going.
the Telerik team