RF transmitter circuit can be safely powered from DC 4.5V to 6V power supply. Here, diode D1 is added to introduce a 0.65V drop, but this is not very crucial
The 434 MHz RF module (Tx &Rx) is available from many sources. Connection terminals are usually labelled on the PCB. In case of any doubt, refer datasheets of the RF modules
In practice, the transmitter is usually powered by batteries. But you can power the receiver from an onboard /external dc supply too. In this case, make an optional “noise filter” arrangement , as shown here, to “clean” the 5V power rails of the 434MHz RF receiver module