About RSS template customization

2 
{{ with .Content }}<content:encoded>
{{ `<![CDATA[` | safeHTML }}
{{ . | safeHTML }}
{{ `]]>` | safeHTML }}
</content:encoded>{{ end }}

or using printf

{{ with .Content }}<content:encoded>
{{ printf `<![CDATA[%s]]>` . | safeHTML }}
</content:encoded>{{ end }}