Tether RF Roundabout

[longstocking]

My baby is in a RF Roundabout that I want to tether to the seat in front of it but I'm not sure it will work.
We have a 1998 Chevy Suburban. Trying to tether to the drivers seat. The only available place that I can find is a bar that's open and goes all across the width of the seat under the back of the seat. I don't really know how to explain it. I wrapped the d-strap around and tightened but the strap can slide along the width of the bar. Will this matter?

 

[Jeni-GAcpst]

Yes, movement matters. You cannot use that bar for tethering. It's considered a moving part of the vehicle. If you want to use the tether for RFing, you need to find a spot that is bolted to the vehicle frame.
Most front seats slide on a vehicle seat track that is bolted to the frame, and the track has some clearance above the upholstery of the floor. If you can slide the d-ring under the seat track and wiggle it back as far as it goes, you can create a fixed tether point.