Custom placement in the theme

Have you tried Source Title field making empty in plugin options?

Yes, although I meant which code should I use in the single.php, so I can control where exactly will the plugin’s output be placed?

There is no separate function to append content in single.php file. Currently sources are appended using the_content filter. Method source_affix_affix_sa_source is there to generate source. You can check that function and develop your own function to display sources.

Closing ticket.