Put footer/signature on every blog post?
I see 3 pretty easy solutions :


(The easiest) You add a new field textarea to your blog content type. You configure its default value to the content you want (your blog footer content) which can be html (so you're free to type in whatever you want). Then configure the display of your blog post to have this field as the last one displayed. Done.
You can  add a entity_reference field (Entity reference module) to your blog content type. Then create a node which represent your footer, and use it as your default entity_reference field value for your blog content type. (Then you'll have to configure your display modes however you want it ...)
You can probably do this with a hook_form_alter() and insert your footer directly in the form


Hope it helps