I am trimming all my windows interior using WM 366. It's very cheap since I can buy door pack from HD. It looks good on the left, right and top sides but looks ugly if we use that as an apron moulding below the window stool, even if I make returns to both ends.

The profile of the casing is here:

http://www.homedepot.com/Building-Materials-Moulding-Millwork-Moulding/h_d1/N-5yc1vZara1/R-202086608/h_d2/ProductDisplay?catalogId=10053

Has anyone used similar window casing? How do you deal with the apron at the bottom? Thanks!