וְסָמַ֣ךְ יָד֔וֹ עַ֖ל רֹ֣אשׁ הָעֹלָ֑ה וְנִרְצָ֥ה ל֖וֹ לְכַפֵּ֥ר עָלָֽיו׃
И возложит руку свою на голову всесожжения; и будет принято, чтобы он совершил искупление для него.
Rashi
על ראש העולה UPON THE HEAD OF THE BURNT OFFERING — This is intended to include an obligatory burnt offering also in the law of סמיכה (laying hands on the head of the sacrifice) as well as to include a sheep that is offered as a free — will burnt offering (Sifra, Vayikra Dibbura d'Nedavah, Chapter 4 3-5).
Ibn Ezra
He will place his hand [singular] It seems from a literal interpretation of the verse that he places a single hand (for we cannot assume that the scapegoat [16:21] resembles the other offerings, insofar as there Scripture specifically mentions how many hands are to be placed). However, the Exegetes, upon whom we rely, have determined that all laying on of hands involves both hands [Yoma 36a]. The animal which atones for an emergent impulse is called a burnt offering [literally: an arising]. Similarly, the animals brought to atone for sin and guilt are called sin-offerings and guilt-offerings, respectively.
Ramban
AND HE SHALL LAY HIS HAND. This means his two hands, for we find it stated: and Aaron and his sons shall lay their hands upon the head of the bullock;56Exodus 29:10. and Aaron and his sons shall lay their hands upon the head of the ram,57Ibid., Verse 15. and the Rabbis interpreted it to mean: “the hands of each and every individual.”58I.e., the word “hands” does not refer to “Aaron and his sons,” thus implying that each lay one hand, but to each individual laying his two hands on the offering. The source of this interpretation is unknown to me. Thus [it is clear that] both hands were required for it. In the case of the goat designed to be sent [to Azazel] it is expressly stated, And Aaron shall lay both his hands upon the head of the live goat.59Further, 16:21. If so, I do not know why Scripture wrote “his hand” [in the singular] in all other cases of the laying of hands. Perhaps it is for the purpose of deriving therefrom what the Rabbis have interpreted:60Menachoth 93b. “His hand — and not the hand of his proxy.” For had it been written “his hands” [in the plural we would have interpreted it] to require the laying of both hands, and we would not have been able to exclude the proxy. But now that [we derive from other verses that] both hands must be laid upon the offering, [we must conclude that] He only wrote the singular [indicating the hands of only one person], to exclude a proxy, for although a man’s proxy is like the man himself61Kiddushin 41b. in all other places, we should not consider him so in the case of the laying of hands. In Torath Kohanim we find:62Torath Kohanim, Acharei 4:4. “And Aaron shall lay both his hands.59Further, 16:21. This teaches that the laying of hands upon the offering must be done with both hands, and forms the general rule for all cases of laying of hands, that they be done with both hands.”