Hello madame Samanjoonii !! "bisehatek بصحتك" is used by Moroccans in many faced-situation in daily life. We say it when someone is eating or when someone got a shower and when someone bought something new such as clothes, car,... etc. So this expression has multiple usages. When eating it means ''bon appétit'' as you mentioned. If you have any question you are welcome!.

وللرد تقول "الله يعطيك الصحة" and to answer someone told "beshtk" you say "allah yaatiik saha"

in Tunisian dialect it has different meaning from Moroccan. It means "you are lucky !" or " the luck was in your side". And "bon appétit " is صحّة ليك or just صحّة

can I talk to you

Thank you for your comment!