I think you're looking for the Gallery tab. It has buttons at the bottom for loading/selecting reference images.
Once an image is loaded into the Gallery, then you can select it as the Reference image by double-clicking the item in the Gallery contents list.
You don't say which version of Color Finesse you're using. There were some issues with Reference images in earlier versions, so you may want to update to the latest version of Color Finesse, which is 3.0.4. The installer for the latest version is available on our web site and can be installed using your current Color Finesse serial number.
And you would be pretty spot on with that I did need to use the Gallery tab That will teach me to stop, walk away, then come back and read the manual properly
Many thanks for you help.
It would be great if someone could give a clue where to find this Gallery Tab. In my version (AE CC 2017 / macOS), there are no tabs.
Ah, found it! Is just the lowest menu-item in the top left menu (starting with Combo, Reference, ...)
I was looking for a Tab as we are used to in browsers and Windows.