Chabad.org — English translation + Rashi
Torah Temimah points to Zevachim 24a (unit 4; single primary locus per emergency Core plan).
E-Daf.com — Zevachim 24a
HebrewBooks / Shas PDF
English: It was taught: “With his finger and he shall take” — this teaches that kabbalah is only with the right hand; “with his finger and he shall put” — this teaches that application is only with the right hand.
Right-hand requirement for kabbalah and netinah — both receiving and applying the blood of the nasi’s chatas use the right hand.
Kabbalah of the blood and its subsequent application to the horns must both be performed with the right hand. Use of the left hand for either act fails to satisfy the requirement derived from the doubled language of “with his finger.”