Certain elements of the riding habit remain the same throughout the period: the full back, the train, and the tiny peplum in the back (remnant of the longer habit coats of the previous century). But here we also see changes that reflect what is happening in fashion in general. The waist is higher, the shoulder given more emphasis, and more ornamentation overall, as seen here in the braiding on the shoulders, sleeves, and down the front. Another sign of the times is the hat. It is made of cork, which I have not seen in prints before 1818. You can see other examples here and here, both from 1818.
The print is described in the magazine as follows:
“A habit composed of fine slate-coloured cloth; the skirt is of a moderate fulness, and finished up the front with braiding. The body is short in the waist: for the form of it, which is very novel, we refer our readers to our print; it is braided in a very rich manner, as is also the sleeve. Head-dress, a round hat, composed of cork. Slate-coloured leather boots, and Limeric gloves.”