It is not possible to have our feature activate when you create a new web. There is a feature attribute called ActivateOnDefault,
but unfortunately it does not apply to site or web scoped features. However, if you have an active RadEditor feature in the Site Collection and you create new web sites (e.g. a new personal site for a user) then the editor should be active in those new sites as well. This means that the proposed workaround in my last message (changing the scope of the RadEditor feature) should do the job in your case.
the Telerik team