Unable to prepay for checked baggage on economy reward tickets

[WeeWillyWonka]

I've booked a US domestic economy reward seat on AA using Qantas points, but can't find out where (or if) I can prepay for checked baggage. Or can this only be paid at airport check-in?

 

[bam71]

You’ve got the AA Pnr/record locator and tried to access your booking on AA.COM?

 

[WeeWillyWonka]

All I have is a booking reference (and of course e-ticket #) on the Qantas ticket (booked through them on AA metal). That's all I see unless I'm missing something? I can seat select if I log into FMB on Royal Jordanian.

When navigating to manage my booking through the QF website, it states baggage needs to be purchased at check-in. I find this strange as I can pre-pay for baggage on United under a Velocity reward.