Use postman to test signed C# ASMX Webservices

I am developing SOAP api's using C# ASMX webservices which requires signed requests.

I used Postman to automatically test my API. With unsigned requests it's no problem to send the request with Postman.

But since the API requires the request to be signed, it get's more complicated to test it with Postman.

Does anyone have some experience in testing SOAP ASMX webservices which require signed requests with Postman or any other tool?