Anyone using inklewriter - question

In a story I started long ago, I was able to insert a nicely formatted horizontal line.

I cannot figure out how I did this (the story removes the formatting once it knows what you’re doing). Anyone know how this is done, or the page for formatting tips?

I posted this over there and searched for a while, but their forums move very slowly.

Thanks.

In case anyone cares…this turned out that I had used a paragraph with a row of underscores. You can all sleep easy now!!