Can you bottle feed an infant while hes laying down on his back?

Try not to. Feeding a baby in a slightly head up position will prevent any of the formula getting into the middle ear and causing ear infections.
Think of a bottle as. a substitute breast. Nutrition & nurturing go together. Hold your baby with his head up at least 30 degrees to prevent reflux of milk into the middle ear tubes, even when he can hold his own bottle at 5-6 mos. Look at your baby, as your face will be about 12" away from his, best distance for him to see early on Smile & coo if it doesn"t distract him. Never prop bottles or use a bottle holder.