Composers and Performers

For identified albums Roon offers an excellent tagging service. But for unidentified album how can I add the performers as well as I see them on the album identified by Roon?

For composers is easy I use the tag “Composer” on my files and is ok but for Performers how should I do? such tag should I use?

The tag you need is PERFORMER. That works independently(-ish) from ALBUM ARTIST.

Try it and see how you get on.

If you do classical Roon also recognises CONDUCTOR and SOLOIST although currently it hides the latter.