ויקרא ב:ט פירוש: רש״י, Siftei Chakhamim וחזקוני

את אזכרתה ITS MEMORIAL PORTION — this is the “fistful” (קמץ) (cf. Rashi on v. 2).

The fistful. [Rashi knows this] because it is written above: “The kohein shall separate from the meal-offering,” and afterwards it is written: “its memorial portion and burn it on the altar...”

והרים, “the priest will lift off, etc.” just as this procedure mentioned in chapter 6,8 consists of a fistful of the priest’s three middle fingers, קומץ, so this is also what it means here, though the Torah does not mentions a quantity.