וְאֵ֗ת עֹרֹת֙ גְּדָיֵ֣י הָֽעִזִּ֔ים הִלְבִּ֖ישָׁה עַל־יָדָ֑יו וְעַ֖ל חֶלְקַ֥ת צַוָּארָֽיו׃
И она надела шкуры козлиных детей на его руки и на его шею.
Chizkuni
.הלבישה על ידיו, “she placed on his hands and arms.” The reason why she took goats’ skins was that these hairs are harder than those of sheep and more closely resemble human hair.
Radak
Rivkah also covered Yaakov’s throat and arms with the skins from the goats so that Yitzchok would think that Esau was indeed standing before him.