Your mistake is very simple. I will mark it in your message:
> Hi people, i want to set a rate limit in my proxy server, i have 2mbps
> and i want to limit the proxy to 768kbps, reading the pf faq i found
> some examples, but its not working, i only want to limit the bw, not to
> do qos, i only addedd these lines to pf.conf
>
>
> # queues
> # 750 kbps max to/from internet
^^^^--- No, nothing cannot control the "from" the internet.
> altq on fxp0 cbq bandwidth 768Kb queue { std }
> queue std bandwidth 100% cbq(default)
>
>
> i have the interface fxp0 monitored with mrtg and i see >768 kbps right
> now, how can i check what is not working?
>
> thanks