I have a question regarding making hamotzi on Shabbat-
After Kidush hamotzi is said- now if i only eat a bite of the piece of bread that was thrown to me- do i still say Birkat hamazon at the end of the meal? What is considered a kezayit of bread? And if i dont eat that kezayit do i still say Birkat hamazon at the end- since i did do netilat yadayim and said hamtzi?
please let me know since i have this dilemma every week.. thanks!