The fourth stroke is hooked. However it frequently is illustrated in compound characters （like 督) without a hook but this is dependent on the font. In Skritter, the font that appears in my browser as text in the HTML (to the left of the Flash window) shows the hook, Skritter itself does not.
Where as in Pleco the character lookup shows the hook in a compound but the (Apple) font in Pleco doesn't.
Now, normally it's not a big deal but in this case this is a defining feature which Skritter is actually looking for and will mark you wrong if you hook the stroke.