Laws for Yom Kippur Ending on Saturday Night

Adding from the Mundane to the Holy
One must add from the mundane to the holy at the conclusion of Yom Kippur, meaning one should not conclude the holy day immediately at nightfall, but rather wait a few more minutes. Therefore, it is forbidden to eat or perform work immediately at nightfall at the end of Yom Kippur; one must wait a while. It is proper for every person to be stringent not to eat or perform work at the end of Yom Kippur until an hour and a fifth (seventy-two seasonal minutes) have passed from sunset, according to Rabbeinu Tam and the opinion of most early authorities, as we have elaborated on the importance of being stringent according to Rabbeinu Tam's opinion in a special law.

Nevertheless, a sick person who is greatly distressed by the fast, as well as pregnant and nursing women who suffer greatly from the fast, may be lenient and taste a little food after nightfall.

Havdalah over a Cup
One must make Havdalah over a cup of wine at the conclusion of Yom Kippur, just as we do at the conclusion of Shabbat and festivals.

Creator of the Lights of Fire - Year 5778
In the Havdalah at the conclusion of Yom Kippur, one must recite the blessing "Creator of the Lights of Fire," as is customary in the Havdalah of Saturday night. The reason we recite this blessing every Saturday night is because the creation of fire was renewed on the first Saturday night, as explained in the Gemara (Pesachim 54a), that at the end of Shabbat, Hashem gave wisdom to Adam, who found two stones, struck them together, and produced fire.

However, at the conclusion of Yom Kippur that doesn't fall on Saturday night, this reason doesn't apply. Nevertheless, we still bless over fire because during Yom Kippur it was forbidden to kindle fire, and now the permission to kindle it has been restored. Therefore, we recite "Creator of the Lights of Fire" for the renewal of the permission to kindle fire.

Therefore, one must ensure that the fire used for the blessing is from a candle that "rested." That is, a candle lit before Yom Kippur, or a candle lit from another candle that was burning since before Yom Kippur, which during Yom Kippur itself was forbidden to use for lighting fire, and now, at the conclusion of Yom Kippur, it is permitted to use it to light fire.
If one does not have a candle that was burning since before Yom Kippur, according to our master Rabbi Ovadia Yosef of blessed memory, in any ordinary year, one should not recite the blessing "Creator of the Lights of Fire" at all. However, this year (5778), when Yom Kippur falls on Shabbat anyway, someone who doesn't have a candle that rested can bless over a regular candle that was just lit. This is because we bless over the candle for the same reason we bless over it every Saturday night. (Responsa Yechaveh Daat Vol 1 #63, and Chazon Ovadia on the High Holidays p. 383).

Creator of Various Spices
In the Havdalah at the conclusion of Yom Kippur, one should not bless over spices. Even this year, when Yom Kippur falls on Shabbat, one should not bless over spices. Nevertheless, our master of blessed memory wrote (in his book, p. 384) that it is good to bring spices after tasting from the cup properly, and then bless over them.

From Strength to Strength
It is a mitzvah to increase eating and drinking with joy at the conclusion of Yom Kippur, and the Midrash says that at the end of Yom Kippur, a heavenly voice proclaims, "Go, eat your bread with joy and drink your wine with a good heart, for Hashem has already accepted your deeds" (Ecclesiastes 9).

Those who are meticulous in performing mitzvot begin building the sukkah at the conclusion of Yom Kippur, in order to go from one mitzvah to another, and about this it is said, "They go from strength to strength."