Hi,
I found that the article does not exactly answer this question. Normally, adding a regular field will add it to the header (if you are not at maximum header fields yet). Since you want only three fields in the header, you will need to do this a bit differently.
The field you make should not appear on the header and only appear on the header flyout.
For field “xyz” that I want to appear on the header flyout (drop down), and not appear on the header:
Create an Input component for said field.
Click on the input component attached to the field, and uncheck the Appear on formats checkboxes
Now you have an input field that doesn't have the strange input appearance
