Bill, like most things in Xara, there are many solutions.

If you precede your text with a Space on a line above then SaT will stop at that Space.
So you then adjust the font size of the Space to that of the difference between the original text hitting the top of page and where you actually want it to stop.

As it is a one-liner (now two), you could adjust the Line spacing but easiest is probably using the Baseline shift on the Space.

Acorn