When at that stage you can just press ( and it will prompt you for the overloads.
Take this example:

I press ( and I get:

If I happen to change focus, I can go back into the call at this.M1( and press Ctrl+Shift+Space (or ⌘+Shift+Space on macOS) to get the overload prompt again:

Pretty much the same as Visual Studio.
This is in VS Code 1.7.1, C# 1.4.1 extension.