well understand your need to use liquid fertilizer to feed your roses. I have used gravel/rock mulch around my roses for years. Usually I feed all of my roses with an organic or organic based rose fertilizer in the Spring, then do the liquid applications from then on. When I apply the granular fertilizer (either Gro Rich Rose and perennial food or some other organic or organic based fertilizer), I just sprinkle it on top of the gravel around the base of the rosebushes. Then with a small long handled hard toothed rake, I jiggle the gravel a bit to let the granules move down further into the gravel mulch. Then water each rose bush well to wash the granules down further and the nutrients do get where they need to be. For the liquid fertilizer, I like to use Urban Farm Rose Garden Fertilizer. Link> https://www.amazon.com/Urban-Farm-Fertilizers-Garden-Fertilizer/dp/B00AYJ4AZ8 It is an organic mix that feeds not only the rosebush but helps build the soils home of the rose bushes as well. I also mix in feeding the rosebushes with some Miracle-Gro Multipurpose liquid fertilizer as well. It gives the roses a little something different to eat that way. I use the Urban Farm Rose Garden fertilizer the most though due to its organic nature. The Miracle-Gro used too often can cause soils salts issues so I do not recommend using only the Miracle-Gro. I do not worry about getting their mix that says it is for Roses as I have never seen any difference in performance between the two. The amount of product I get with the Urban Farm product and how far it goes makes it a truly fine choice. Here is a link to their website as well: https://theurbanfarm.com/rogash.html .
