1 RF emisor, many Receptor

Hi, how can i use one RF emisor on Arduino, to send signals to many Receptor BUT only the ones i choose, e.g: i want to activate only receptor numer 8 but ivgot another 7 thats need to ignore the order, because i just one number 8 to work. excuse my bad English. thanks

It might be simpler to have all the receivers receive all the time, but only act on what they receive if they receive the right code from the transmitter