Originally Posted by
commaspace
It looks like it works as a referral site, like Rakuten or Honey, so it shouldn't matter which card you use as long as you don't have a competing referral site add-on activated.
What's interesting, though, is that they sometimes offer different percentages based on the card you select (to enter the store?). Right now it's all 5X for Saks, but the regular deal seems to be 2X for CFU and 1X for CSR.
The few times I have used the Chase UR portal I have used the actual card that had the highest percentage, so no idea if there is any validation.