I've used snowshoes a few times but never carried them. How do I attach them to a rucksack when not being used?
I found that one of my rucksacks had straps on the side that were ideal for fastening snowshoes to.
The others in the group had a lot of bother and various unsatisfactory ways were utilised. The most common way was to trap them under the lid of the sack; this was a bit dodgy when it was snowing.
One thing worth noting, the modern type of snowshoe, with fancy ratchet strap tightening fittings ( ours were TSL 325) lasted about 5 minutes until the plastic strap snapped. Luckily the shoes were hired; we all ended up with good old fashioned nylon straps and had no bother with them.