Commentary for Genesis 24:14

אתה הכחת HER THOU HAST APPOINTED — She is fit for him since she will be charitable and will therefore be worthy of admission into the house of Abraham. The word הכחת means selected; old French approuvest; English thou hast selected.

HER THOU HAST APPOINTED FOR THY SERVANT, EVEN FOR ISAAC. Rashi comments: “She is fit for him since she is charitable and worthy of admission into the house of Abraham. And thereby shall I know — this is a petition: ‘Let me know through her that Thou hast shown kindness unto my master.” If so, Eliezer is saying, “I know for certain that You have appointed her for Your servant Isaac.” But in that case [his petition, which still indicates a doubt as to whether she was the appointed one,] does not connect well.
Its interpretation however is as follows: “Make it happen to me this day that the girl to whom I will speak be the one that You have appointed for Your servant Isaac, and with this, show kindness to my master Abraham for with this I will know that You have shown kindness to him if she be of his family and of good mind and of beautiful appearance.” And so he said [when recounting the events of the day]: And let it come to pass, that the maiden, etc., let the same be the woman whom the Eternal hath appointed.¹¹²Further, Verses 43-44.

אותה הוכחת, she is the one whom You have appointed to be Yitzchok’s wife. The word אותה excludes the possibility of any other girl being the proper wife for Yitzchok.