Microdata is supported in AMP but RDFa is not.
Here is the source of the mark-up below: [http://schema.org/CreativeWork]

Microdata:

<div itemscope itemtype="http://schema.org/CreativeWork">
<span itemprop="name">Resistance 3: Fall of Man</span>by 
<span itemprop="author">Sony</span>,Platform: Playstation 3 Rated:
<span itemprop="contentRating">Mature</span>
</div>

RDFa:

<div vocab="http://schema.org/" typeof="CreativeWork">
<span property="name">Resistance 3: Fall of Man</span> by 
<span property="author">Sony</span>, Platform: Playstation 3 Rated:
<span property="contentRating">Mature</span>
</div>

AMP validator throws the following errors on RDFa mark-up:

The attribute 'vocab' may not appear in tag 'div'.
The attribute 'property' may not appear in tag 'span'.

There are other RDFa object properties, such as about, rel and compact URIs (CURIE), that also are rejected. A CURIE is in the form xmlns:owl.

When <amp-img> is used in place of <img>, AMP validator rejects 'property' in both Microdata and RDFa mark-up.

Will the Google AMP team consider supporting RDFa mark-up in AMP documents?
Will you support Microdata and RDFa mark-up for AMP-specific elements such as <amp-img>

/jay gray