@Hina Yasir Thanks for reaching out. I don't see any properties for the built-in or azure connector for IBM MQ that can set the RFH header while sending the message. The Send Message or Send Message V2 doesn't have any property as per the documentation. So unfortunately, you cannot use any other fields that are not configurable in the connector.
The workaround would be leveraging the REST API of the IBM MQ if there are any and calling them over HTTP action from logic app.
Feel free to provide your feedback here if this is something you want to see in IBM MQ connector.