https://www.youtube.com/watch?v=f1t7bC4_Nto&t=2869s
Even with this tutorial I think there are some clean-ups needed with the User Interface... which I'll suggest with a screen grab.

To explain:
1. The red IOR field row isn't labelled properly.
2. N and K fields aren't identified
3. It would be tremendously useful to users if the RGB 'N' and 'K' vales could be populated by selecting from a menu of common metals. It is a major pain to collect/calculate/enter these values. Selecting one of the presets would auto-populate the correct values for all six fields. If it's too much fuss to add these presets in a menu...then it would be really nice to have a 'cheat sheet'. By cheat sheet I mean a pop-up where we could at least see the values for common metals....Perhaps re-key or copy-paste them from there.
4. This isn't referenced in my screen grab....but also...since the "Creative" iOR option uses the specular color, I recommend displaying that color value there... if that mode is active.