These images are 98 pixels tall per 98 pixels wide and fully transparent.
EDIT: just checked and yes, these fit on forum signatures!
EDIT 2: added the occupation images for kitten jobs!
Hunter
Gatherer
Miner
Fisher
Bug Catcher
Gardener
Herbalist
Farmer
Flockherd
Apothecary
Clothier
Scribe
Artist
Blacksmith
Craftscat
Builder
Mason
Baker
Tiny Adventurer
Leaf Collector
Cricket Hunter
Garden Helper
Crafts Helper