This plugin will display an image showing the number of comments on a post at the bottom of each feed item (RSS|Atom|etc) that links to the comments section of that post. 
You are able to choose which colors to use for the background of the image and the color of the text as well. 
The reason you would want to use an image instead of plain text is because RSS feeds are generally only updated if the build-date or modification-date components are changed, which does not happen if someone leaves a new comment. This will allow the comment number to update dynamically, regardless of when it’s been first viewed by a user.
You’re able to set the colors of the text and the background in the standard 6 character hex format. 
You may also supply formats for what will show if there are zero comments on your post or more. 
I just added the option to include the image link in the feed excerpts as well. (called by <code>the_excerpt_rss</code> function)
Two Font files are included with the plugin, Arial and SenateBold. You can set which of the two you would like to use, or optionally upload your own .ttf font file to use to render the text on the image.
This requires the GD Image library extension in PHP to function. To check whether or not your server has this use the <code><?php php_info(); ?></code> function and it should be listed.

Feed Comments Number

Add an image that displays the number of comments to your feed items.

GNPublisher

GN Publisher makes RSS feeds that comply with the <a href="https://support.google.com/news/publisher-center/answer/9545420" rel="nofollow ugc">Google News RSS Feed Technical Requirements</a> for including your site in the <a href="https://publishercenter.google.com/" rel="nofollow ugc">Google News Publisher Center</a>.
The plugin addresses common RSS compatiblity issues publishers experience when using the Google News Publisher Center, including:
<ul>
<li>Incomplete articles</li>
<li>Duplicate images</li>
<li>Missing images or media</li>
<li>Missing content (usually social media/Instagram embeds)</li>
<li>Title errors (missing or repeated titles)</li>
<li>Cached RSS feeds causing slow updating</li>
<li>Delayed crawling by Google</li>
</ul>
After installing, click on the ‘Dashboard’ under GN Publisher on your plugins page for additional information about applying and troubleshooting issues related to the Google News Publisher Center.
New in 1.5.24 
Compatibility with Apple news publish
New in 1.5.11 
Google Reader Revenue Manager support.Reader Revenue Manager provides publisher solutions to deepen audience engagement and convert subscribers or contributors.
New in 1.0.9
GN Publisher now displays the time of the most recent ping and feed fetch from Google. This helps when troubleshooting the dreaded ’empty sections’ issue in the Google News Publisher Center.
New in 1.0.6
GN Publisher now pings Google when feeds are updated. This can help with faster updates in your Google News Publication.
<h3>Support</h3>
We try our best to provide support on <a href="https://wordpress.org/support/plugin/gn-publisher/" rel="ugc">WordPress GN Publisher plugin support forum</a> forums. However, We have a special <a href="https://gnpublisher.com/contact-us/" rel="nofollow ugc">team support</a> where you can ask us questions and get help. Delivering a good user experience means a lot to us and so we try our best to reply each and every question that gets asked.
<h3>Bug Reports</h3>
Bug reports for GN Publisher: Google News Compatible RSS Feeds are <a href="https://github.com/ahmedkaludi/gn-publisher/issues/" rel="nofollow ugc">welcomed on GitHub</a>. Please note GitHub is not a support forum, and issues that aren’t properly qualified as bugs will be closed.
<h3>PRO Version</h3>
Take you Google News Feed experience to next level by using our <a href="https://gnpublisher.com/pricing/#pricing" rel="nofollow ugc">GN Publisher PRO</a> plugin which contains the following features.
<ul>
<li>Content Scraping Protection </li>
<li>Exclude Categories From Main Feed </li>
<li>Google News Sitemap </li>
<li>Compatibility with Flipboard.com</li>
<li>Compatibility with PublishPress Authors</li>
<li>Compatibility with Translate Press</li>
</ul>

GN Publisher: Google News Compatible RSS Feeds

GN Publisher makes RSS feeds that comply with the Google News RSS Feed Technical Requirements for including your site in the Google News.

Feed Comments Number vs GN Publisher: Google News Compatible RSS Feeds