A.     When we approach an Orthodox Priest, we seek his blessing:  By bowing from the waist such that our right hand touches the floor*, than as we raise up we place our right hand over the left hand with palms upward, we say, "Oce Blagoslovi." (Father Bless**)    The Priest then answers, "May the Lord bless you," and blesses us with the Sign of the Cross by forming his fingers into a Christogram, and places his right hand in our hands.   We then kiss  his hand.

The reason that a lay person kisses the hand of a Priest is to show respect  to  his   Apostolic  office.   More importantly,  because the  Holy Mysteries  are held  in the hands  of the  Priest  during the Divine Liturgy,   when we kiss  his hand,  we show respect to the Holy Eucharist.