Answering Kedusha While in Shemoneh Esrei

If im in the middle of my personal amidah, and im up the first yehi ratzon (before elokai), should I say kidusha with the minyan when they get to it?

Shalom!

Thank you for your question.

Here are some of the rules relevant to your question.

One who is in the middle of saying the Shemoneh Esrei is not to answer any of the communal responses. This is because the Shemoneh Esrei is the central and most important section of our daily prayers allowing us a private audience with the King of kings.

One who hears Kedusha during one’s recitation of the Shemoneh Esrei is to pause, remain silent, and merely listen to the chazzan’s recitation of “kadosh, kadosh, kadosh…,” and “baruch kevod…” One then resumes one’s Shemoneh Esrei. Some sources allow one to remain silent and listen to the entire Kedusha.

As you note, after one finishes the main body of the Shemoneh Esrei one is to say the verse “yihiyu l’ratzon…” Once one has said that verse, one is now allowed to respond to the two verses of Kedusha just mention above along with everyone else. No need to remain silent and just listen to them. Furthermore, I will note that once one has said the “yihiyu l’ratzon…” verse, one has the same status and rules as one who is in the middle of the blessings of the Shema in terms of what one may respond along with everyone else.

At the end of the concluding paragraph of the Shemoneh Esrei “Elokai netzor…” one says “yihiyu l’ratzon…” once again. One who is unable to take the three steps back as is customary at this point, such as because there is someone behind you still reciting the Shemoneh Esrei, is permitted to answer to all communal responses, including all “amens” and even “baruch hoo u’varuch shemo”

Sources: OC 104:7, 122:1; Mishna Berura 122:1-4; Aruch Hashulchan, OC 104:13; Chayei Adam 25:10