You need to use 5.4dev version and it will work: https://discuss.pixls.us/t/download-rawtherapee-development-builds/2924
Fuji X-T100 is newer than Raw Therapee 5.4 
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Btw, what do you think about the 15-45mm? I think it’s yet supooted via lensfun btw (https://wilson.bronger.org/calibration).
I have the 16-50 and i must say i have been surprised with its quality, much better than i expected! Despite being rather slow it’s really sharp.
Thank you.