On windows, I wrongly thought this feature was present in 5.2. I don’t remember when it was added. It will be present in 5.3
With this feature, when installing with installer (not with zip) you have the possibility to add “browse with Rawtherapee” to the directory context menu.
If you want you can test
RawTherapee_dev_5.2-187-ga1f86bff_WinVista_64.zip
available at https://drive.google.com/open?id=0B2q9OrgyDEfPS2FpdDAtMVI1RG8