Saying Yihiyu Leratzon at the end of Chazaras Hashatz:
Some Poskim rule the Chazan is not required to recite the verse of Yehiyu Lertatzon at the conclusion of his repetition. Other Poskim however rule the Chazan is required to recite the verse of Yehiyu Lertatzon at the conclusion of his repetition. Practically, the custom is like the former opinion although it is proper to suspect for the latter opinion [and so is the custom today].
The Chazan is to recite the verse of Yehiyu Leratzon at the conclusion of his repetition.
 Admur 123/8
 Stam opinion in Admur ibid; Rama 123/6; Darkei Moshe 123/5; Beis Yosef in name of Ohel Moed
 The reason: As he relies on the sentence of Tiskabeil Tziloshon which he will say at the end of Kaddish. [Admur ibid; M”A 123/14]
 2nd opinion in Admur ibid; Shelah Inyanei Tefila, brought in M”A ibid; Elya Raba 123/12; Soles Belula 123/4; Gr”a; Derech Hachaim; Kitzur SHU”A 29/7; Ashel Avraham Butchach 268; Shulchan Hatahor 123/5; Birchas Habayis 42/20; Mamar Mordechai 123/13 and Kaf Hachaim 123/30 in their understanding of Beis Yosef and Michaber ibid and that so is Sefaradi custom; Shalmei Tzibur p. 47 and Kaf Hachaim ibid in their understanding of Shaar Hakavanos that so is the proper custom based on Kabala
 Admur ibid; However see Mamar Mordechai ibid and Aruch Hashulchan 123/8 that the custom is like the latter opinion.
 Admur ibid; Chayeh Adam 29/2; Majority of Poskim, as brought in previous footnotes; See the two opinions in Admur 122/1 and the final ruling there
 Piskeiy Teshuvos 123/7