I am not familiar with an in-depth discussion of Ritzuy among the Kollel's work, but I will give you a general overview:

1) Rabeinu Yonah writes (in Sha'arei Teshuvah, Sha'ar 1, #42) that when someone does Teshuvah he should pray to Hash-m to blot out his transgressions so that Hash-m should delight in him, desire him ("Yirtzeihu," which is derived from the word "Ratzon" or "Ritzuy"), and accept his prayer as if he had never sinned. Rabeinu Yonah cites Iyov 33:26: "He prays to Hash-m and Hash-m is favorable (Yirtzehu) to him."

The Sha'arei Teshuvah writes that it is possible for the transgression to have been forgiven and redeemed but still Hash-m has no desire for him and will not accept ("Ritzuy") a Korban from his hand. The greatest success desired by the Tzadikim is to gain Hash-m's favor ("Ratzon") and that He should delight in them.

2) It seems from this that Ritzuy is a high Madrega, higher than mere forgiveness attained through the Korban. In fact, the Gemara (Zevachim 35b, immediately before the Mishnah) states that Akum do not acquire "Hartza'ah." The Midrash Tanchuma (Parshas Ha'azinu #4) tells us that if we do Teshuvah, Hash-m will "raise up His face towards you" but this is only "Eilecha" -- "to you " (Bamidbar 6:26). Only to Klal Yisrael does Hash-m raise up His countenance, not to any other people.

3) Rashi (Zevachim 13a, DH Lo Yeratzeh) writes that Ritzuy comes through Zerikah, sprinkling the blood on the Mizbe'ach. Rashi explains further (28b, DH Mah Hartza'ah) that Hartza'ah is obtained only by Zerikah, which is the last of the four Avodos of the Korban. Ritzuy is the summit of all of the stages of the Korban.

Kol Tuv,

Dovid Bloom