Chris;
Yes, that's the one. However, since your car did not come with the fog light option, there may be no switch there. It may be just a dummy knob. Take a look under the dash and see if the knob is connected to a switch. If there's nothing there, your going to have to get one. I don't have a convertible, but I believe this knob was also used to operate the top. For non convertible cars without the fog light option, this knob had no function.
Paul