Beginner question on RetopoFlow 2.0 Beta

Is this the best forum for asking questions about RetopoFlow?

I just bought the add-on, and I’m trying to get my head around it. Right now I’m stuck on what I think should be a simple thing… I am practicing with the Contours tool, and I am able to create the contour loops pretty easily. But let’s say I want to go back and adjust a loop I created earlier in order to adjust it… How do I select a loop? The help file says I can use CTRL+SELECT / CTRL+SHIFT+SELECT for this, but it does not seem to work for me. What’s the trick?

I am running on an iMac Pro, Mac OS High Sierra if that matters.