Lets say there are 5 (png/tiff) outputs of a file, each being ‘edit on edit.’ In the end number 3 is the best. How to load the parameters of 3.png.out.pp3 in RawTherapee?
Open that file with RT doesn’t do anything. Don’t see an option in RT to open pp3.
Is the only way to copy the content of 3.png.out.pp3 to xxx.NEF.pp3?
When editing an image, you can load a profile on the Profile panel, top right of the notebook. You can also only load part of it (see the tooltip). In the File Selector, an entry on the left side will let you choose the location of the edited image, for convenience.
Aaaaaand @TooWaBoo is the winner ! 
Oh really that easy…thanks guys.
I really thought I tested that button and nothing happened. I guess I am mistaken.