Is there a way to finish the dart end in a sheer fabric without leaving a thread tail or knot at the point?
A single thread dart has no thread tail or knot at the point, so it's perfect for sheer fabrics:
Unthread the machine needle. Thread the bobbin thread backwards through the needle and tie it to the upper thread with a square knot (Figure 1).
Pull bobbin thread backwards through needle and tie to upper thread.
Slowly hand-wind the bobbin thread back up onto the thread spool until the knot reaches the spool. You now have one continuous thread from the bobbin to the spool.
Stitch the dart from the point to the wide end, the opposite of the traditional method. Set your stitch length at 20 stitches per inch and put the needle into the fabric exactly at the fold. Stitch 1/2" along the dart stitching line, then switch to a regular stitch length, changing back to 20 stitches per inch for the last 1/2" (Figure 2).
Stitch dart from point to wide end.