See here:
https://sites.google.com/site/daxrnorman2/analysis
The structure used there should easily transfer to OpenSources, both the website and the script, especially since it already has MANY similarities to the one currently already used by OpenSources.
This would provide both a numeric trust score and based on that, a High/Moderate/Low/Not Credible trust scale.
Note that the criteria and weight values originate from survey input from 66 professional intelligence analysts!