אורח חיים ק״לOrach Chayim 130

Se’if 1א׳

מָאן דַּחֲזָא חֶלְמָא, וְלָא יָדַע מַאי חֲזָא, נֵיקוּם קָמֵי כֹּהֲנֵי בְּשָׁעָה שֶׁעוֹלִים לַדּוּכָן וְנֵימָא הָכֵי: רִבּוֹנוֹ שֶׁל עוֹלָם, אֲנִי שֶׁלָּךְ וַחֲלוֹמוֹתַי שֶׁלָּךְ וְכו', וִיכַוֵּן דִּלְסַיֵּם גַּם בַּהֲדֵי כֹּהֲנֵי, דְּעָנֵי צִבּוּרָא אָמֵן; וְאִי לָא, לֵימָא הָכֵי: אַדִּיר בַּמָּרוֹם שׁוֹכֵן בִּגְבוּרָה, אַתָּה שָׁלוֹם וְשִׁמְךָ שָׁלוֹם, יְהִי רָצוֹן שֶׁתָּשִׂים עָלֵינוּ שָׁלוֹם. הַגָּה: וּבְמָקוֹם שֶׁאֵין עוֹלִין לַדּוּכָן, יֹאמַר כָּל זֶה בְּשָׁעָה שֶׁהַשְּׁלִיחַ צִבּוּר אוֹמֵר שִׂים שָׁלוֹם, וִיסַיֵּם בַּהֲדֵי שְׁלִיחַ צִבּוּר, שֶׁיַּעֲנוּ הַקָּהָל אָמֵן (הָרַ"ן פ' הָרוֹאֶה).

The "Ribono Shel Olam" ("Master of the World") [Prayer] That We Say During the Lifting of the Hands [the Priestly Blessing], Containing 1 S'if: One who saw a dream and did not know what one saw should stand before the Kohanim when they ascend the platform [for the priestly blessing] and say this: "Master of the world, I am Yours and my dreams are Yours, etc.". And one should aim to finish along with the Kohanim [finishing their blessing] as the congregation answers "Amen". And if not [i.e., if one finished before the Kohanim finished their blessing], one should say this: "Majestic One on high, Who dwells in power, You are peace and Your Name is Peace. May it be Your will that You bestow peace upon us". Gloss: And in a place where they do not ascend the platform [to perform Birkat Kohanim], one should say all this while the prayer leader says "Sim Shalom" and finish along with the prayer leader as the congregation answers "Amen" [to both]. (The Ran - chapter "Haro'eh" [Talmud B'rakhot, Chapter 9])