I have used RTI as the remote for AMX systems several times. There are a few ways to do it.
#1 get a AMX RF receiver 433mhz (Good way)
#1 Put in an RP6 and a cm232 or whatever the RTI part number is for a 232 adaptor and run the 232 to AMX then get or right an AMX module to do what ever you want when it receives 232 info.
#3 Get a AMX TCC television controller with an IR receiver and have the RTI RP6 or Rp1 spit out AMX IR commands

All this requires you to program AMX as well

But I must say the RTI/AMX combo rocks if it done right