Publishing SharePoint via ISA Server is fairly straightforward, even if you use SSL to the reverse proxy, and connect on port 80 to the SharePoint server in order to move the encryption load from your SharePoint box.

However, for some reason, this appears to break Telerik’s RadEditor.  In order to use RadEditor, you need to be able to connect directly to the server in the same format of the initial request, which means in the case of a secured SharePoint site, SSL.   Simply change the bridging rule to redirect requests to the SSL port, and disable redirection to the HTTP port.  This will place more load on your SharePoint servers – every request is encrypted via SSL between the SharePoint server and the proxy – weigh this load up against the editing benefits of RadEditor.