If you are only calling a Remote Function Module in SAP system, you don’t require any configuration in SM59.
Considering a scenario where your SAP system has to call a function in the C# application, then you need to configure RFC destination using SM59. You can Transaction for defining HTTP destinations- SM59.
There are two types of HTTP connection:
Note that both the connection types differ from each other in terms of logon procedures. The technical settings are same for both connections.