Can't Annotate a PDF+Text file?

I created many RSS feeds. I wrote some Smart Rules to cull unwanted stuff from them.

The feeds come in as HTML texts. Which are not a format you can annotate with simple things like highlights or underlinings etc.

When I convert any of these HTML files to PDF+text they STILL are not annotatable in DevonThink 3!

However, if I locate one in the finder and use another app like PDF Pen Pro or PDF Convert, they ARE annotatable and I can create highlights etc.

Other PDF+texts I have created from say an original bookmark file I captured (not via RSS feeds) work fine.

So is it just impossible to convert HTML Text into an annotatable PDF?!

TIA

Only items outside of a feed are editable. Does your smart rule perform this too?