There are different traditions for formatting stage directions, even in publications of the same play. When quoting stage directions, your aim should be consistency.
It is most common to find stage directions in italics, and you should replicate them:
After Levan states that Homais “faints,” the stage directions detail what happens next: “She sinks down in a Chair, he falls at her feet” (22).
If it’s not clear from context that you are quoting stage directions, indicate this in your in-text citation:
Manly’s scene concludes on a passionate image: “She sinks down in a Chair, he falls at her feet” (22 [stage direction])
To indicate that the quoted material is a stage direction, some scholars use the abbreviation sd after the line number: (120sd). But in an essay that is not specialized in theater history, it would be better to avoid mystifying your readers with that technical detail.
Stage directions typically appear in parentheses or square brackets. When quoting stage directions and dialogue together, follow your source’s use of parentheses or square brackets if you can:
“Her salt tears fell from her, and soft’ned the stones,
Lay by these—
[Singing.] “—willow, willow”—
Prithee hie thee; he’ll come anon—
“Sing all a green willow must be my garland.
Let nobody blame him, his scorn I approve.”
But if you quote from sources with variant practices, choose one method for enclosing stage directions and be consistent.
The names of the characters in stage directions are often given in different ways—roman and all capital letters, small capitals, or a combination—but in your manuscript simply make them italic, with the rest of the stage direction:
“Enter Nurse wringing her hands, . . .”
Published 7 August 2017