David Morrison's personal on-water surfski safety kit
This is as much for would-be rescuers as for you. You stand a better chance of getting your lost gear back if you have identification printed on it. But you may also save someone a search mission to find you if they can get in contact with you when they discover any of your equipment.
You can also visually distinguish your gear with a tape color and/or pattern - particularly helpful when multiple paddler's gear is loaded in a trailer or piled on shore close together.
In the USA, boats over 16 ft have flare carrying requirements with the following exceptions that let surfskis off the hook for expensive fines:
Despite such exceptions it is a good idea to carry flares that are not old, particularly if you boat at night, and/or alone, and/or in waters that are challenging, remote, or have volatile water or weather conditions.
Carrying a tow rope can help save equipment, paddlers and yourself. You can make tow rope with 20 feet of cord and two light carabiners. Clip the one carabiner to your rear handle and the other to the disabled ski's front handle or foot brace. If you attached it to the foot brace the paddler in the disabled ski will need to steer. (If you do not have a rear handle you can add a secure attachment point using well nuts and pad eyes (carabiners are too large for small pad eyes so also add a cord loop or something larger to hook the biner to) or some other type of secure mount (all parts should be marine grade))