Hi,
There are very few (if any) commercial offerings of adapters that allow an RTF file to be consumed and parsed in BizTalk. You would have to build your own custom pipeline component in a project to parse the data from an RTF file and put it in XML format that BizTalk understands, but I would recommend saving yourself the time and effort if you can have the file generated in text or XML format.
Btw, if you are not doing any transformation or processing of the RTF file through BizTalk, but just simple routing (messaging-only scenario) , then use the Pass-Through Receive pipeline in your Receive Location, and have a Send port subscribe to your Receive Port to redirect the file to your desired location.
Daniel.