Do I need to purchase a template in addition to Mobile Joomla

I noticed in the documentation:

Smartphone Settings:
Template: template name to use in this mode (can be set to empty in the case of responsive main template)

Does this mean if I have a responsive template I do not need to purchase an additional template?

Yes, if your main website's template is responsive, you can use it with MobileJoomla. MJ gives you a way to reduce mobile page size by rescaling images, to disable modules and plugins in mobile version, etc.

I downloaded the Free version as suggested to determine comparability.  As I make changes to the configuration they do not seem to have any effect on the appearance of the page on my iPhone.  I purchased your "Insider's Guide" to see what I might be missing and after going through the first 20 pages I still don't seem to have an effect on the look of the mobile version.

I host the site at HostGator and I am using a responsive template called Lt Business.  Is there a comparability issue?  Is there more I need to do?