Cho Dream,

Are you an experienced Finale user?

I am not sure how detailed directions you need.

You can get a 1-line staff via a staff style.

If the rhythm sheet’s barlines should line up with the barlines above, add an extra staff to the document (use the Staff Tool).

Hide the extra staff where you do not need it.

If the rhythm sheet does not have to line up, add an extra system for the rhythm sheet (use the Page Layout Tool).

In the extra system, hide the staves you do not need.