We decided to get some clarification out there for you. Coaches have different interpretations of the rule and it is leading to some issues.
First and foremost, it is only applicable to teams that play 7v7.
The GK cannot punt the ball. They can throw / roll to their team mate. They can also put it on the ground and play with their feet (pass to a team mate).
If it is a goal kick, then they must kick the ball in, but not past the build out line.
Punts or drop kicks result in an indirect freekick to your opponent from where the ball was kicked.
If the GK for the other team gets the ball (either a goal kick or picks up the ball), your team MUST move back behind the build out line.
Your team can move back to the ball once the ball is ‘in play’ from the GK. ‘In play’ is the ball being played by the GK. The exception is goal kicks, whereby the ball must leave the penalty area before your players can move back into the game.
Note that the GK does not have to wait for the other team to move back behind the build out line.
Talk about the rule with the referee and the opposing coach. Make sure you are all clear. Enforce the rule with your own team and help to remind the other team if they forget. It only works if we all work together and this is being implemented by US Soccer across the nation, so please help with your team and your games!
Further reading. Official US Soccer release for 7v7 soccer, including the build out line.