Create own 'social' icons

I am using this theme on my site https://www.berryplasman.nl, with a child theme.

I use the social icons to display some of my profiles, but I would like to link to another profile with a custom image, which you can see on the site; it’s the logo for the Dutch Downhill Division website.

I added the image in the menu as such:

wp_nav_menu( array(
	'theme_location' 	=> 'social',
	'depth'          	=> 1,
	'link_before'    	=> '<span class="screen-reader-text">',
	'link_after'     	=> '</span>',
	'items_wrap'		 	=> '<ul id="%1$s" class="%2$s">%3$s<li class="ddd"><img src="'. $stylesheetdir.'/images/logo-ddd.jpg" class="ddd" alt="Proud member of the Dutch Downhill Division" /></li></ul>'
	)
);

I would like to add a link to it, but how do I do this ? Because if I add one in the code above, the standard link icon is displayed (f103 I think), which I don’t want.

Any solutions ?