By default, posts to Facebook and Twitter will have a "via Sendible" tagline below each post. To have this changed, you can apply for rebranding by going to http://bit.ly/sendiblerebranding.
Once we've setup the rebranding for you, you'll be able to add the custom services from within this section.
For more information see, Can I change 'Via Sendible' to 'Via My Company'?
For a list of the social media services supported by Sendible, see What Social Media services do you support?