The QD appears to be just ahead of where the foot attaches (about 1/3 of the way forward).
Why after waiting to see the RRS design I bought a Kirk I did not want that removable foot and extra knob. Kirk worked great and very well made. I am using the past tense since I sold the Z180-600 and the Kirk collar/foot assembly,One knob to tighten the collar, the other to tighten the foot on the collar. Kirk's doesn't have a removable foot and doesn't need a spring loaded safety feature.