I don't believe there is a way, from within Skitch, to send the photos more than one at a time. I looked all over the app - couldn't find anything like that. Maybe another can find it?
So, I guess you'll just have to do the "normal" way: If you've saved them (from within Skitch) to your stock Photos app, then you can go into the Photos app and mail them from there (up to five). Or, you can copy them from the Photo app to put them into your e-mail.
Apologies for repeating the process - but others reading may not have known the "normal" way of e-mailing photos from the iPad...
Marilyn