Use the following guideline to get your LoR:
1. Ask them to write you a letter.
Well, I hope this helps. 👍
Being slightly more serious for a second (though i was being pretty serious before...), they know you'll be asking for a letter--it's letter season, after all. Ask them, but be prepared with your CV and unofficial transcript, too. They might want to set-up a formal meeting where they sit down with you and ask you questions, or they might not need anything and just write you something. But you first gotta' ask. For the PD, I'd make a formal appointment and come prepared with all your papers.
Good luck, dude.