How to add a horizontal line in RoboHelp HTML 7

HI - I am working with RoboHelp 7 HTML. I want to add a horizontal line to my topic. I am using RoboHelp as my editor. Work mostly in WYSWYG / Design mode and don't do much hand coding as a rule, but sometimes I tweak the code. Since I couldn't find a WYSIWYG way to add a horizontal line, so thought I would try the<hr/> tag.

Sadly - that just shows up on the Design view page as a big, red highlight of the <hr/> tag.

Suggestions?
Thanks, Leisa