A few words from someone that has lost hives to bucket feeders.
Make sure that you use very small holes in the lids, also very few
holes. Make enough syrup to fill the buckets completely. Turn the bucket
over outside of the hive to ensure a tight seal allowing the bucket to
drip and form a  vacuum. Then place them on the top bars. You can shim
or not for bee space, once they find the syrup they will spread the
word. This is also a good time to treat for Nosema with "Fumidil B".
   I have lost hives to leaking buckets and it is really a bad feeling
going down an opening your strong hive to find the healthy cluster is
soaked with sugar water and dead. I have lost 3 hives this way over the
past 2 winters. Keeping only two hives you can see where this is a very
costly mistake. Last spring I paid over $115.00 for replacement bees.
Good Luck
 
Gary C. Lewis
Duke Center, Pa.