You need to uncover the roots/rhizome on the anubias or it will melt. Only the rotala and "hedge" will benefit from osmocote capsules is the lone stem of rotala. You could put one directly under it, and then add more as you add root feeding plants. If you ever add a foreground stem, stick some more in.
You have a few choices to make. With my JBJ, it's a low light no Excel tank that is anubias and java fern filled. Or, you can go higher light, Excel and root tabs and start adding faster growing stems. If you are adding numerous anubias, you might get some driftwood or rockscape and tie the anubias to the hard points.