How should I recline the car seat when used rear-facing?

When using the restraint rear-facing, lift up on the recline handle and adjust the seat to one of the three rear-facing recline positions so that the level line is parallel to the ground. Infants may have difficulty breathing when in an upright seated position, so make sure they recline enough for their head to lie back comfortably and safely. In some vehicles, you may need to place a rolled towel or small blanket beneath the front edge to achieve the proper recline. (Page 28)