Are you talking about the Forte or the Forte SE? (I don't know if it makes a difference, but it helps us to look at the correct manual.)
In the Forte manual, it looks like the Metronome might be available only in Song mode, but I'm not sure. There's a Metronome parameter in the Song mode which determines when the Metronome will sound, and if you set it to "Always" then it will sound both while recording a song and while playing back a song.
If the metronome only sounds in Song mode, you could try recording a bar of silence (if that's possible), then use the loop mode to keep looping that bar with the metronome set to "Always," so it will hopefully keep sounding continuously while you practice.
Note that I have zero experience with Kurzweil, so all I can do is try to go by what's in the manual. I believe that Gary/
@happyrat1 has a Kurzweil, although I'm not sure which model it is, so he might be able to help.