I want to write a client application with RTC that comunicate with a 3rd part php web service.
If you're writing a client to talk to a 3rd party web service, PHP is irrelevant. All you need to be concerned with is the API exposed by the web service.
I'm guessing that the web service exposes a
RESTful API? If so, as Danijel mentioned, you'll need the TRtcHttpClient and TRtcDataRequest components to send the appropriate GET, POST, PUT & DELETE requests exposed by the web service API.