You have indicated you are not using Semantic Sass for your project. This means you will not be able to edit theme files, as they will be baked into the CSS file.
How to select a theme
Kickstart only requires you to import one single sass file to use the library (The CSS portion, anyway.) This one file is your chosen theme!
To switch themes, you'll need to find this
@import and make it point to the
theme you'd like to use.
If using a clone of the repository, you can find this in style.sass. If using Rails, this can be found in application.css.sass. See shimming for Rails for more information