Depending on context it may not actually mean "F". Screen readers are not yet capable of fully understanding the meaning behind the text they are reading.

If for example someone uses this to write a mathematical formula, having a screen reader says "F" changes the entire meaning.

Could this be done, absolutely, but it is something to be aware of and is something I noticed on Twitter where blind users were complaining that they were unable to "read" Twitter messages using this, thereby making them second class citizens all over again.