By default the RadScriptManager combines automatically all requests for scrips used by our controls. In case an external resources need to be combined, they should be embedded in assembly. The good news are that as of Q1 which should be released tomorrow, RadScriptManager will be able to combine requests for script defined only by path. In case you have scripts loaded by the ScriptResource.axd handler, they could not be combined by the RadScriptManager.
All the best,
the Telerik team
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