The guide should touch the antlers first in most cases.. he is the person who actually did all the hunting. Most anybody can make a shot within the kill zone of a big game animal at reasonable distances, but very few people can get within shooting distance of trophy size animals often. If you need the guide, or even want one just because of lack of time and energy to do the scouting yourself then you give up the hero "I touched it first" argument.
Precisely why I've yet to hunt with a guide. Someday maybe - but part of what makes it a hunt for me - is to know that I did it myself -really. If someone is with me when I recover my deer - It doesn't bother me in the least if he/she gets to it first - I know that I hunted the animal - in no uncertain terms.
FH