@mikesan I don’t know what is your system.
If it is windows you should find recent development builds here https://discuss.pixls.us/t/download-rawtherapee-development-builds/2924 .
Choose the dev branch build “RawTherapee_dev_5.0-r1-gtk3-124-gb84e570f_WinVista_64.zip” or more recent.
As it is a deveolpment build, option files are located in …/rawtherapee5-dev