When you enter the beer, there should be a place where you can describe any special ingredients or processes.
Here is the relevant section of the rules from the competition we just held yesterday:
For entries in category 23 (Specialty/Experimental/Historical), the brewer must specify the experimental nature of the beer (e.g., type of special ingredients used, process utilized or historical style being brewed), or why the beer doesn't fit an established style. The brewer may specify an underlying beer style. For historical styles or unusual ingredients/techniques that may not be known to all beer judges, the brewer should provide descriptions of the styles, ingredients and/or techniques as an aid to the judges.
So in our registration form, there were "base style" and "special ingredients" fields, as well as a "comments" field. Both of those fields were then printed out on the score sheets & flight summary sheets that the judges used when judging the beers. It is particularly important to describe the beer in the appropriate fields on the form(s), or else the judges don't really have a frame of reference by which to assign scores.