Yeah I'm on a 10.5 Leopard.
I found this on another website; you have to open "Customize Toolbar" from the "View" menu at the top. And then add the "Annotate" icon to the menu bar. From there I can use that tool now.
It's still grayed out when I manually try to open it from the "Tool" menu though.
Anyway; it's working now.
Thank you again..