I don't know how to do this with R2 but if you have t and p-values for the coefficients, than all variables with p>0.05 are insignificant (if p-values are calculated correctly). Generally, adjR2 are too small for the applicable model. I can say exactly due to my experience - 1. there are redundant variables in this model 2. This model is garbage even if it is statistically significant ( - not applicable). Tip to the author of article - identify the most significant predictor and say that there is a weak correlation. This will be honestly. Other is pseudoscience.