Stereo install with toggle switch.

[Sergio]

That is the typical "5 wire" converter, that thin red wire is the +48v trigger.

That diagram depiction of the "load" is confusing as refers to the pins in the plug.

How You wire it depends on how you want not only the radio but all other accessories 12v power to be controlled.

If You want all accessories to be powered on/off at the same time just put that red thin wire directly to the key switch so +12v is only available when the switch is ON or to a separate on/off switch that is powered from the key switch if you want to manually control when +12v is available.

If you want to just control the radio, use either option above to power the converter but run Your radio red wire to an on/off switch that connects to the converter +12v output.

Keep in mind that turning the converter OFF will cause your radio to loose presets if the radio needs "constant" power to preserve the memory.