[Plugin: Simple Tags] How to autotag posts from external RSS-feed

I’m using the WP-o-matic plugin to import various RSS-feeds as posts to my WP-blog. Furthermore, I am using SimpleTags for autotagging of posts that I manually create.

When the posts that are imported by WP-o-matic are saved the autotag is not executed and this might be the intended design of the SimpleTags plugin.

How can I enable autotagging when posts are imported? Is there a way to do that by using SimpleTags or is there some other plugin/workaround available?!?