To search your post render file, js, jsx, the name just like PostContent or Post, my site file name is PostContent.js and I’m using casper theme. First of all, I was imported disqus-react component, Github repo, secondly, imported configrations following:

// on the top
import Disqus from 'disqus-react';

const PageTemplate: React.FC<PageTemplateProps> = props => {
....

  const disqusShortname = "your-disqus-name";
  const disqusConfig = {
    // make sure your props and set it.
    url: config.siteUrl + props.pathContext.slug,
    identifier: props.pathContext.slug,
    title: post.frontmatter.title,
  };

Finally, you need to use component in render callback:

<Disqus.DiscussionEmbed shortname={disqusShortname} config={disqusConfig} />