I read that and saw such things as:
Specify the output color profile; the saved image will be transformed into this color space and the profile will be embedded in the metadata.
The main histogram, navigator and clipping indicators will use either the working or the output profile, depending on your setting in Preference > General.
RawTherapee comes bundled with a number of custom-made high quality output profiles:
But nowhere in Preferences do I see anything about setting the output profile, nor do I see it in the Save dialog, only Display and Soft-proofing.
Update on Soft-proofing: the three profiles I uploaded have appeared in the Color profile drop-down. Apparently, a restart was needed. My mistake.