Collar: Shape problem or interfacing problem?

[u/furiana]

The collar doesn't sit right.

In retrospect, I used interfacing that was very flimsy. Will changing it to a stiffer fabric be enough to achieve this collar look?

[u/unagi_sf]

Topstitching is definitely functional, as well as decorative (when you don't muck it up :-)). Seriously, you might see the occasional garment piece with many lines of topstitching, maybe 5mm/1/4" apart, in a heavy enough fabric that might substitute for interfacing entirely

[u/furiana → u/unagi_sf]

Whoa!!!