Currently it’s not possible to use the WPSP social icons on the single post. WPSP doesn’t alter the single post at all, as those are controlled by the theme you’re using.
This might be something we’ll look into adding in the future, but it may be outside the scope of the plugin.
At the very least I’ll try to make it so you can add them using a function.
For now, it may be better to use a plugin and use CSS to style them somewhat similar.