Small amounts. It would be hard to use Propofol for light sedation. It is the drug we reach for when requiring deep sedation which means that the patient is not responsive to verbal stimuli. There is a fine line between deep sedation and general anesthesia ( airway is easily obstructed unless someone is there to maintain patency). One can look up dosages but everyone is different and require different amounts.
Why. This is an unusual question and is something that a trained doctor or professional providing sedation knows.
Medical question. This is not a question that should be given to a lay person outside of a consult with an anethesiologist. It suggests illegal use.