Attaching Panning to Return Air Duct?

[Phil]

Got the supply ductwork in for the upstairs unit. Ready to start on the Return air ducts.
I know my questions are a little simplistic and my wife says I overthink everything but:
Does anybody attach the panning under the floor joists to the return duct or just run it up to the hole cut into the top of the ducts?

[rabadger]

They do it both ways. Make sure it's sealed from leaks.

[Phil]

Thanks Richard. You have been a lot of help.

I just figured out what the pieces that I have been calling standings are used for. The standings are something else which are sturdier S strips for the 27" air ducts. My supplier has funny sizes. All his ducts are odd widths such as 27", 23", 19", 15", etc.
The pieces I was worried about are bent into an L shape and put behind the drywall to support the return vent screws. You bend 2 to make a rectangular frame for the air vent. My wife is right, I'm overthinking everything again.

[MCC]

Panning Is Fine And A Lot Of Times Less Noisy