Using FTDI with AtMega328P@3v3,8MHz and RFM69
It sounds and looks from your schematic as if you may be attempting to power the project from the FTDI chip's very limited 3v3 regulator.

If that is the case you are probably overloading it, especially when the radio is added.

You should at minimum give your project its own 5v to 3v3 regulator (along with the capacitors that typically requires) if not a dedicated power supply.  Of course you need a common ground with the FTDI for communication.