I’m not sure you can do this on the Receive side. The Adapters are written to handle a lot of messages… not really throttle down to a specific number.
Assuming each message starts an Orchestration or is in a Convoy, you would do this via a custom process. Using a counter inside a database, process X messages per interval. It would all be custom code inside an Orchestration to read / write to a DB table.
Other than maybe a custom Adapter, don’t really think of another way to do it.
Hope this helps.