The USBF Open Rules on this website say:
A team not present within 15 minutes of scheduled start of the game will forfeit the game.
Clubs may have house rules that govern late show ups. We have seen tournament protocol where teams have been granted a certain number of points every five minutes until the maximum are reached. An example might be to award 2 points every five minutes that a team is late. After 30 minutes the game would be scored as a 12 point victory for the team that was present. This is somewhat lenient and gives a team a chance if they were late due to reasons beyond their control.
The final decision on forfeits should be up to the club or organization hosting the tournament. But it must be kept in mind that awarding less than the maximum points to the team that is present penalizes them unfairly in the event that points are used in tiebreaker situations, whether in tournament play or end-of-season league play. The team may have been able to score the maximum number of points had the game actually taken place. Awarding maximum points for the forfeit gives them the benefit of the doubt.
The rules on forfeits should be announced or posted prior to the start so that everyone is on the same page! Whatever protocol might be in place; USBF rules or house rules, USBF rules forfeits are scored as complete games – usually 12 to 0.