If you're using a granulated fertilizer, which I usually do when I use fertilizer, you can just shake it on the mulch. As it degrades, the microscopic particles will find their way to where they need to be. You can also see when it's gone that way.

After multiple applications of compost, mulch, leaves, the decomposition of old roots, the digging of holes, the soil will become much more rich and fertile in time, depending on your additions, frequency, weather, original soil... In older beds, I don't find any need for fertilizer. Quite useful in newly-claimed areas though, especially if they were lawn.

Keep working on your soil and you can forget about that stuff sometime soon...