You don't need to add the Scripts and Skins folders to your application as far as you use the scripts and skins, which are embedded in the Telerik.Web.UI assembly.
FYI, the Scripts and Skins folders are distributed in a hotfix to support the cases where customers prefer to output the accompanying RadControls scripts and skins manually (e.g. by declaring the <link> and <script> elements).
I hope this helps.
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