According to wikipedia, in regression problems, consider 2 models, the F-statistic is $$F=\frac{(RSS_1-RSS_2)/(p_2-p_1)}{RSS_2/(n-p_2)}$$, where $p_1,p_2$ are the degrees of freedom of the 2 models respectively, $n$ is the sample size.

I can't understand $F$ intuitively, since I see that $F$ seems to be ratio between RSE of the 2 models, and it is used to choose the model which better fits the data, right? How to interpret the numerator in $F$, $(RSS_1-RSS_2)/(p_2-p_1)$?