default or selected kernelversion does not have config value CONFIG_SERIAL_68328_RTS_CTS.
Result is shown for kernelversion 6.5.1

Support RTS/CTS on 68328 serial port

configname: CONFIG_SERIAL_68328_RTS_CTS

Linux Kernel Configuration
└─>Device Drivers
└─>Character devices
└─>Serial drivers
└─>Support RTS/CTS on 68328 serial port
In linux kernel since version 2.6.20 (release Date: 2007-02-04)