After all evidence and argument have been heard, the Senate must vote. The vote is separate on each Article of Impeachment. If no Article registers a two-thirds vote for conviction, a judgment of acquittal is pronounced and recorded. If one or more Articles of Impeachment receive a vote of two-thirds or more, then the president is convicted, and judgment of conviction and removal is pronounced by the chief justice.
So if the Senate approves a single article of impeachment--by a two-thirds (66/100) vote--then the Chief Justice would pronounce conviction and removal. While in the current circumstances it seems unlikely that enough Republicans would vote to convict, if this should happen (and what's now impossible in politics?), then what would happen to the office of the presidency? Would the vice-president wait outside the Senate chamber to take the oath from the Chief Justice? What would constitute an orderly transfer of power? Of course, all the talk of a "coup" is horse-hockey. The vice-president is selected by the president and is also a Republican. But still, Trump has no sense of party loyalty or continuity, unlike Richard Nixon, who did not hesitate (at least publically) about allowing Gerald Ford to become president without any question about Ford's legitimacy to ascend to the office.
Black, Charles L. Jr. & Bobbitt, Philip, Impeachment: A Handbook, New Edition (p. 13). Yale University Press. Kindle Edition.
