Jekyll Custom SEO tagging that works better with Siteleaf. This is really similar to the Jekyll SEO tag plugin except it lets you override the og image with a custom image if you have one. If there isn't a custom image, it takes whatever image is on the page.

jekyll-seo-pluggin.html

<title>{{ page.title }} - {{site.title}}</title>
<meta property="og:title" content="{{ page.title }}" />
<meta name="description" content="{{ page.excerpt | strip_html }}"/>
<meta property="og:description" content="{{ page.excerpt | strip_html }}"/>
<link rel="canonical" href="{{site.url}}{{page.url}}" />
<meta property="og:url" content="{{site.url}}{{page.url}}" />
<meta property="og:site_name" content="{{site.title}}" />
{% if page.og-image %}
  <meta property="og:image" content="{{ site.url }}{{ page.og-image }}" />
 {% else %}
  <meta property="og:image" content="{{ site.url }}{{ page.image }}" />
 {% endif %}
<meta property="og:type" content="article" />
<meta property="article:published_time" content="{{ page.date }}" />
<script type="application/ld+json">

{"@context": "http://schema.org",
"@type": "BlogPosting",
"headline": "{{ page.title }}",
"image": "{{ site.url }}{{ page.image }}",
"datePublished": "{{ page.date }}",
"description": "{{ page.excerpt | strip_html }}",
"url": "{{site.url}}{{page.url}}"}</script>

With this set up, you're able to use Siteleafs smart field names so your user can use the 'file fields' and have a more visual selector.