The Markdown Viewer in Komodo is accessible from your toolbar whenever you are editing a file that has a Markdown association. When you hit the preview button the editor will split in two and show you a preview for your markdown file. Any alterations you make to your file will automatically be reflected in the preview.
That’s really all there is to it. We have a lot more ideas for where we want to take this going forward, please feel free to share yours also!