Rule Question from the newbie
 

Rule #2, Art. 9 (NFHS)
When the runner misses the plate, and on an appeal from the defense, the plate OR the runner can be touched for the out. Does this mean that if bases were loaded either plate or runner can be touched and if a tag was needed for the (normal) out then the the runner has to be touched and touching the plate wouldn't get the out?

Nope....means just what it says.

If any runner misses the plate, the appeal can be made by tagging the runner (while in possession of the ball) OR touching the plate while in possession of the ball (live ball appeal). A dead ball appeal can be made by just telling the umpire that the runner missed the plate.

As with any appeal....the defense needs to do something to let the umpire know what they are appealing and which runner the appeal applies to.

BTW....welcome! :)