Originally Posted by
rambutan
Now I'm trying to put this in my SQ profile so it's there for future flights. But on the SIA website I cannot find any place to do this.
It is located in the booking flow when you make a new reservation involving a US origin or destination. It prompts for a "known traveler number" along with a redress number, if applicable. It may or may not be able to be added to traveler details after the booking is ticketed -- have not tried that yet.
I do not think you can have it saved in your profile permanently as of yet, but if you add it when you make the reservation, it should work for TSA Precheck. Has worked for me on the last few flights after SQ began participating in the Precheck programme.