<p>I have an <strong>"ldquo"</strong>, <strong>"rdquo"</strong> and several other entities under my RSS feed. Seems like if I add</p>

<pre><code>&lt;!DOCTYPE rss [
  &lt;!ENTITY % HTMLspec PUBLIC
  "-//W3C//ENTITIES Latin 1 for XHTML//EN"
  "http://www.w3.org/TR/xhtml1/DTD/xhtml-special.ent"&gt;
  %HTMLspec; 
</code></pre>

<p>below the <strong>xml</strong> tag and above the <strong>rss</strong> tag then I'll be able to include those entities. I added but it doesn't seem to work. Does anyone knows what I missing? Thanks</p>

it doesn't seem likely that many feed readers will know what to do with that.  i would recommend sticking with numbered entity references.  for example, change
```
&ldquo;
```
to
```
&#8220;
```
.  you can get the full entity reference
right here from w3c
.
additionally, you can read
this article
and
this one
which gives some good tips on this topic.