Note that these are different scenarios and the editor's activation for them is different.
If you want to use the editor in List Items scenario (Wiki content
, etc.) please review the following help article:
If you want to use it in Web Content Management scenario please review the following one:
As to the site template, when you create a new page in MOSS (Site Actions --> Create Page) a new page is opened - the Page Title, Description and Layout
have to be chosen there. In order to achieve the desired behavior you need to modify the Page Layout template so that, when creating a new page the default editor to be automatically replaced with RadEditor. Please, see the attached screenshot.
the Telerik team