Hello,
Well, I'm not quite sure from your description what do want to achieve. However basically for repeater you need to specify path, transformation and document type, you want to show. Please see more details in our Developer's Guide:
http://devnet.kentico.com/docs/webparts/Kentico_CMS_WebParts.htm#_0384da9a-d259-4919-8d89-0521262a3713If you want to show repeater only on certain pages (which are based on particular document types) you can use 'Show for document types' property with advantage.
If it doesn't meet your needs please provide us with detailed scenario, what you want to obtain.
Best Regards
Ondrej Vasil