Both are OK.

The mark is the trademark. The trademark of the scarf is usually on the front, but this is just the opinion of most people. The trademark can also be placed on the reverse. Therefore, the trademark can be used both inside and outside.

Both sides can be used, because normally scarves do not have front and back sides. Most scarves have the same material and feel on both sides, so they can be used as front or back. However, according to the habits of many people, the scarf's trademark is usually left outside to allow others to see the brand clearly.