JSON Feed RSS for Textpattern CMS (v4.7+)
Full standalone template page (no plugin needed: smd_thumbnail is optional).
<txp::config /> is a form created to store some global TXP variables (this template uses only one: <txp:variable name="blog_pages" /> in order to set your blog (articles) section name.
Create a page named rss-feed and copy/past the entire template in it. Attach this page to a rss-feed section. Done!
Special thanks to Oleg (Core Dev) who show me how to escape the author's link in a JSON format.