Create feed_by.xml

assets/feed_by.xml

@@ -0,0 +1,12 @@
+---
+layout: compress
+permalink: /feed_by.xml
+---
+
+{% assign posts_by_author = site.posts | where:"author", page.url.params.author %}
+{% for post in posts_by_author %}
+  <entry>
+    <title>{{ post.title }}</title>
+    <link>{{ post.url | relative_url }}</link>
+  </entry>
+{% endfor %}