Where to top up power steering oil on peugeot 206?

You open the bonnet and look for a belt driven pulley approx 125mm in diameter, attached to this is the integrated power steering reservoir, this is a black plastic bottle with a black screw cap. Basically instead of being on the bulkhead or elsewhere in engine bay separated by pipework as were. On the 206 they have simply pressed on the reservoir bottle to to top of p.a.s

pump. The unit comprises 3 main parts 1; pump,2;resevoir and 3;pressed pulley. All units look very similar !!!! and OE part number is only visible on inner/engine side of pump.