I like to use a gallon paint can... Poke about five holes in the lid. fill with syrup, put the lid on, turn upside down and wait for it to stop dripping, and put it either over the hole in the inner cover, or ON the top of the frames, depending on time of year... later fall on the frames is fine, spring, summer and early fall you might find new comb attached to the can. If you have no flow they will be very great full !
Pollen sub in the spring..... I have litterally seen by bees dive bomb the stuff... hitting with a tiny PUFF of the pollen substitute, wiggle all around in it, and then ZOOM back to the hive... you will know if they don't need it because they will ignore it... like syrup. If they have a flow they won't go for the syrup with much excitement...