greetings, I have a notice under php7 : Notice: Undefined variable: GK_TEMPLATE_MODULE_STYLES in /home/xxx/public_html/templates/gk_msocial/component.php on line 22
I'm afraid this template doesn't have such possibility since bootstrap wasn't a standard while it was being developed. You will need to add a link to bootstrap files manually in /layout/blocks/head.php
Sorry, above was an answer to a different question ;/
Is this notice causing any visual issues on site ? I do not think it should, You can just disable showing errors in global joomla configuration for server.