– Take the Type Tool (T) & type the letter “f” on your artboard using the World of Water Font, Bold, with a size of your choice.
– Fill and give a 2 pt Stroke using the same dark gray color.
– Click on Object > Expand twice to expand the text and then apply the stroke.
– Move the letter inside the icon shape and align it to the center.
– You can leave it as it is with the icon shape and the logo as two separate shapes, or you can merge them into a composite path.
– For that, press Unite in the Pathfinder panel followed by Object > Compound Path > Make
– And finally, export it.