We don't have a "form field" that can be linked to Google image directory to select an image and than display it within the article using the F2C templating.
The only option I can think of is that you copy/paste a URL or ID and use inline code in the F2C article template to display the image.
Alternatively there might be a Joomla content plugin that does the job. You can than possibly link that to a form field. I only found modules so fa though: http://joomla30.webkul.com/google-plus-slideshow.html
Hope this helps you a bit.
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