Create an Atom Feed For Google+
Simply replace the highlighted digital number below with your Google+ ID,http://plusfeed.appspot.com/104961845171318028721You can get your G+ ID by clicking profile and then copy the number from your address bar.
Now once you created the Feed URL simply share it with your visitors using this HTML Code,
<a href="http://plusfeed.appspot.com/104961845171318028721" rel="nofollow" target="_blank" >Subscribe to our G+ Updates</a>I have optimized the link so you can safely use it. On clicking the link your visitors will see this page,
From the Subscribe to this feed using option they can choose which service to use to subscribe to your updates. That's all! have fun :)