A sloppy unbuttoned shirt collar is wrinkled and unprofessional.
A consistent, clean and symmetrical appearance upgrades your look to business casual.
Using a seam ripper, open the hem about 1 inch where the collar band meets the placket.
Slide the support down in between the layers of the placket through the opening you created.
Re-sew the seam through the support to secure it in place. Repeat steps on other side of shirt.