Format letter tentang permission?

To, Mrs.Karti

Subject:  Permission Letter

Dear Mrs,Karti

I am Rika, Rahmi's mother. Rahmi will not attend school today,

because she's sick and we told her to rest at home, we will have doctor appointment today and she might attend school again at Monday,14 august 2017. Thank you for your understanding

sincerely 

Friday,11 Agustus 2017.

Mrs. Rika  , Rahmi's mother