since youre tall and skinny i would assume your a hard gainer. if so, bodyweight x 15 = calories needed daily to bulk.
165 x 15 = 2475
so just eat 2500 cals, do a 40/40/20 split and you should be gaining weight in no time.
also, to enhance your appetite, just start eating more, you stomach will expand allowing you to eat larger meals over time. it is best to eat 5 to 6 times a day to keep your body fed and to keep your metabolism working.