How do you determine if a door is Right Handed (RH) or Left Handed (LH)?
Not only besides RH or LH, you need to determine swing direction. Trust me, this needs to be agreed upon. When I built the additional room onto my house, I thought 84 Lumber understood the direction of door swing and they didn't. There is left inswing, right inswing, left outswing, and right outswing.

The door handle on my exterior door is on the right-hand side, but it is considered a left-hand outswing. Whereas my front door swings in, and the handle is on the right hand side so it is considered a right-hand inswing. Make sure you know what you are buying before you spend the money!