Despite what it says in the options page of RPS version 1.3, this plugin doesn’t actually do anything with WordPress Related Posts other than check if it’s installed. After that, RPS just does its own custom query (which does seem to be loosely based on the one used in WordPress Related Posts) to come up with related posts.
Given that it doesn’t work with the current version of YARPP either, I’d say this plugin isn’t very well maintained.
I guess I’ll just have to modify the code myself to get it to do what I want.
We are working on an upgrade for the plugin and will try to incorporate the related posts fetch functionality within “Related Posts Slider”. Probably the next upgrade will have that functionality. I know the dependency especially on YARP is causing so much concern. Till the next upgrade, it is recommended to use “WordPress Related Posts” plugin on RPS settings panel and install that plugin on WordPress as well.
The next upgrade is scheduled to release by first week of January, 2012.
An upgrade for “Related Posts Slider” WordPress plugin has been released (RPS 2.0) and is working fine with YARPP as well as WordPress Related Posts. It is also having a nice single sliding (you can change the number) feature as well.