Using a Felling Foot
Added Sep 27, 2012
The seam made with a felling foot requires much narrower seam allowances. Depending on the seam allowance on your pattern, and the size of your felling foot, you will need to trim some of your seam allowance off before you begin.
You may want to test out your foot first to see how much seam allowance is needed. For my foot, I need about 1/4" seam allowance.
Make sure you're confident about fit before using a flat felled seam, since alterations are difficult and letting the seam out is impossible.