Stephanie Leary

This plugin appends the author’s display name to posts and/or pages. There is an option to turn off the display on your own site, so the signature is visible only in feeds and crossposted content.

Post Signature

Appends the post author's display name to posts. Useful for multi-author blogs that are crossposted elsewhere, such as LiveJournal or Facebook.

macgirvin

This plugin allows you to cross post to your Redmatrix account.
**Note, this plugin converts the html from wordpress into bbcode. 
The bbcode conversion doesn’t handle height and width of an image, so be warned that if you post a very large image that is resized via height and with attributes, those attributes won’t be honored in the resultant post.

Post Signature vs Redmatrix_WP