If you are looking for a brand name I cannot recommend a type that is  finer than another  as the best way to do this is to open up the bags or actually feel the texture of the soil. The easier way to get a fine soil for raised beds is to add Perlite, grit or sand to the soil and work this in well, raking the top layer to form a fine tilth that is better for starting small seeds. Allowing the soil to dry out a bit will help you to work the soil and add soil amendments that will lighten it up. You can also purchase bags of soil made for seed starting. One tip is to fill your beds with a compost topsoil mix or a raised garden bed soil mix and then spread the layer of seed starting mix on top just a few inches deep. Once the seeds sprout the roots will be able to penetrate the deeper and more compost rich soil below.  If you have compost or buy compost you can run it over a sieve or fine screen to remove the large hunks and have just a fine compost mix to use as a mulch for seedlings. Keep growing, Marianne Binetti