The atonement process for an unintentional sin requires precise actions to draw near to God once again. Because this specific offering is brought by an individual or a leader, it functions as an external sin offering. Its blood is applied to the outer altar in the Tabernacle courtyard, reflecting the specific nature and severity of the transgression [חזקוני, רשב״ם, רד צ הופמן, הירש].
A regular priest begins the process by receiving the blood [ביאור יש״ר]. This collection must be performed with the explicit intention that it is for a sin offering [תורה תמימה]. It is universally agreed that both the collection and the subsequent application of the blood must be done with the right hand [רלב״ג, תורה תמימה, אדרת אליהו]. Furthermore, the collection requires direct human action; the procedure is invalid if an animal were to somehow cause the blood to reach the priest's hands [תורה תמימה].
The method of handling the blood involves specific physical actions that have generated discussion among scholars. The primary approach is that, unlike other offerings where blood is dashed directly from a vessel, the priest dips his finger into the collected blood and smears it onto the altar [שטיינזלץ]. Because the initial collection from the slaughter must be done with a vessel, some clarify that the use of the finger applies exclusively to the later application of the blood, not its initial collection [מלבי״ם]. Another perspective suggests that the mention of the finger implies the act of grasping. In this view, it alludes to the fingers holding the service vessel, or perhaps the priest forming a sort of handle with his finger to grip the vessel securely [הכתב והקבלה, פרדס יוסף].
The priest then ascends the ramp of the altar and turns to the right, applying the blood to the four corners in sequence: southeast, northeast, northwest, and southwest [רלב״ג, רד צ הופמן]. Applying the blood to all four corners symbolizes encompassing the entirety of life, assisting the sinner in re-establishing a proper moral path [הירש]. While it is commanded to apply the blood to all four corners initially, the atonement remains valid even if it was applied to only one corner [תורה תמימה, הירש]. The procedure specifies the outer altar of the burnt offering to prevent any misconception that the blood should be applied to the inner incense altar, as is the practice with certain other sin offerings [מלבי״ם].
After applying the blood to the corners, the priest pours out what remains. While he is initially required to collect all the animal's blood into the vessel during the slaughter [מזרחי, גור אריה], the pouring refers only to the leftovers in the vessel, since a portion was already used on the altar [רש״י, רמב״ן, מזרחי, שפתי חכמים, רלב״ג, ביאור יש״ר, גור אריה, משכיל לדוד]. If the blood was collected in multiple cups, the remainder of the first cup is poured at the base of the altar, while the contents of the remaining cups are poured into the drainage canal [תורה תמימה]. This pouring must be done deliberately from top to bottom onto the roof of the altar's base, rather than being dashed against the altar wall [מלבי״ם].
Most commentators agree that the remaining blood is poured at the southern base of the altar. This location is determined by the natural path of the priest's movement. Just as the remaining blood of inner sin offerings is poured at the western base—the first base encountered when exiting the sanctuary—here, as the priest finishes circling the altar and descends the southern ramp, the southern base is the very first one he encounters [תורה תמימה, אדרת אליהו, רד צ הופמן, מלבי״ם].