Hi @manjotsingh057,
Do you want to call WCF service to execute a SQL Server stored procedure with HTTP action of Microsoft Flow?
I think we could call WCF service to execute a SQL Server stored procedure with HTTP action. The HTTP action only support five Authentication type currently: None, Basic, Client Certificate, Active Directory OAuth, Raw.
When you create a HTTP action to make a call to WCF service within one authentication type of above types, you may face with a authentication failure, you need to check if you have provide proper credentials for the http request.
Best regards,
Kris