I was mistaken. The RSS feed will show older items.
All that plugin does is add
<link> elements for each custom post type to your site. If you view the page source and search for
rss+xml you will find three
<link rel="alternate" type="application/rss+xml" title="מודעות אבל" href="http://www.avelim.co.il/feed/" />
<link rel="alternate" type="application/rss+xml" title="תנחומים" href="http://www.avelim.co.il/comments/feed/" />
and a little further down:
<link rel="alternate" type="application/rss+xml" title="מודעות אבל » Testimonials Feed" href="http://www.avelim.org.il/testimonial/feed/" />
which is a separate feed for your testimonials.
The main feed and the comments feed are built into WordPress. A feed for a custom post type, e.g.
mysite.com/testimonial/feed, should work with
public set to
true which we've done, but it's not added as a
<link>, hence the need for the plugin.
<link>s at all? To make it easier for feed readers to discover all the feeds on your site.
Try this if you're looking for a single feed containing both regular posts and testimonials.