Usage of this field is simple:
Put desired fields into intro view of user content type (e.g. a,b,c fields)
Put this field into Content view of your article (or any content type that has author as one of the fields). lets say ariticle has fields d,e,f,g, and you put this field on the last place.
This will display whatever user has put into his fields inside the article, so displayed fields will be
d,e,f,g, and then a,b,c from the author.
You can see this in action here in the About the author section at the bottom http://joogpot.eu/knowledge/16-webdesign/57-evoke-emotion-through-typography