The r.a.d.menu MCMS skin is not officially included in the available archives at http://www.telerik.com/skins, and that is why you were not able to download it. We will consider including it in the future.
In the meantime, find attached the .psd file for that particular skin.
Please, do not hesitate to get back to us if you have futher questions on the .psd or .css file.
the telerik team