식사하신 is composed of
식사하(다)+시+ㄴ
식사하다 means "have a meal" 吃饭
시 is an honorific addition
ㄴ is past tense modifier
식사하시다 is honorific expression of 식사하다
식사하신 금액 means "cost of meals(which you had)"
적혀 is composed of
적히(다) + 어
적히다 is a passive verb of 적다
적다 means "write"
적히다 means "be written"
어 is a connecting particle
적혀 있다 means "it is written"
계산서를 보시면 식사하신 금액이 적혀 있습니다.
You can see the receipt in which the cost of meals is written.