Buick 2006 Rendezvous Owner's Manual page 72

3. Buckle the belt. Make sure the release button is
positioned so you would be able to unbuckle the
safety belt quickly if you ever had to.
1-66
4. To tighten the belt, push down on the child
restraint, pull the shoulder portion of the belt
to tighten the lap portion of the belt and feed the
shoulder belt back into the retractor. If you are
using a forward-facing child restraint, you may find
it helpful to use your knee to push down on the
child restraint as you tighten the belt.