The wedding ceremony under the Hupa begins with the "Birkat Erusin," which the Rabbi recites over a cup of wine. This Beracha concludes with the phrase, "Baruch Ata Hashem Mekadesh Amo Yisrael Al Yedeh Hupa Be'kidushin." The letter "Bet" at the beginning of the word "Be'kidushin" is "Refuya," meaning, it does not have dot. For this reason, many people mistakenly recite the word as "Ve'kidushin," as though it was written with a "Vav," rather than a "Bet." Our practice in any event is to pronounce the letter "Bet" as "B" regardless of whether or not it has a dot, and therefore the Rabbi who recites this Beracha should ensure to pronounce the word as "Be'kidushin," and not "Ve'kidushin."
Before reciting this Beracha, the Rabbi should instruct the bride and groom to have in mind to fulfill their obligation through his recitation of this Beracha. The Rambam (Rabbi Moshe Maimonides, Spain-Egypt, 1135-1204) and the Shulhan Aruch classify this Beracha as a "Birkat Ha'misva," meaning, a Beracha recited before the performance of a Misva, in this case, the Misva of Kidushin (betrothal). As such, it is the bride and groom who should, ideally, recite this Beracha. The custom evolved for the Rabbi to recite this Beracha on their behalf in order to embarrass those who are unable to recite it. Thus, since the obligation to recite this Beracha essentially rests upon the bride and groom, they must have in mind to fulfill their Misva through the Rabbi's recitation. Similarly, they should not answer "Baruch Hu U'baruch Shemo" during the Rabbi's recitation, as this would constitute a "Hefsek" (interruption). They must also have this intention when listening to the Rabbi's recitation of the Beracha "Boreh Peri Ha'gefen," as this Beracha is recited on their behalf, as well.
After the Rabbi concludes this Beracha, he should sip some of the wine before giving the glass to the bride and groom. If he does not drink some wine, the Beracha of "Boreh Peri Ha'gefen" that he had recited might constitute a "Beracha Le'batala" ("wasted" Beracha). Generally speaking, one may not recite a Beracha over food or drink on somebody else's behalf, unless the person reciting the Beracha intends himself to partake of some food or drink requiring that Beracha. Thus, one may not recite the Beracha of "Boreh Peri Ha'gefen" for somebody who wishes to drink wine unless he – the person reciting the Beracha – will also drink wine. An exception to this rule is a situation such as Kiddush or Habdala, where the Beracha of "Boreh Peri Ha'gefen" is included as part of the Misva, as the Misva requires a cup of wine. In the case of "Birkat Erusin," it is unclear whether or not the Misva requires a cup of wine, and we are thus uncertain as to whether the Beracha of "Boreh Peri Ha'gefen" may be recited on the bride and groom's behalf. The Rabbi must therefore drink some of the wine, so as to ensure that the Beracha is valid.
Later in the Hupa ceremony, a different series of Berachot – Birkot Nisu'in – is recited, also over a cup of wine. In this instance, however, the consensus among the authorities is that a cup of wine is, indeed, required by Halacha. Strictly speaking, therefore, the Rabbi who recites "Boreh Peri Ha'gefen" does not have to drink any of the wine. Nevertheless, Hacham Ovadia Yosef (Halichot Olam, vol. 2, p. 204) rules that one should preferably drink a sip of wine even after this series of Berachot, in order to satisfy all opinions.
There is a widespread custom for the groom to break a glass at the conclusion of the Hupa ceremony, in commemoration of the destruction of the Bet Ha'mikdash. Hacham Ovadia writes that it is customary to use specifically a glass utensil for this purpose. Broken glass, as opposed to other materials such as earthenware, has the possibility of being fixed, and thus serves as a fitting symbol of the destroyed Temple, which we hope and pray will be reconstructed speedily and in our day.
Summary: The concluding phrase of the "Birkat Erusin" recited under a Hupa should be pronounced, "Mekadesh Amo Yisrael Al Yedeh Hupa Be'kidushin." As the Rabbi recites this Beracha, the bride and groom should have in mind to fulfill their obligation through his recitation. When the Rabbi completes the Beracha, he should sip some wine and then give it to the bride and groom to drink. After the "Birkot Nisu'in" recited at the end of the Hupa ceremony, it is preferable for the Rabbi to drink a sip before giving it to the bride and groom, though strictly speaking this is not required. After the ceremony, the groom breaks a cup, which should be made from glass.