I too have a surname which is more commonly a forename, I have only ever come across 2 other person with it as a surname and the spelling is 1 letter different. There is also at least 2 different spellings of it. The first letter is pronounced as a different letter to the one used in the spelling.
Many years ago people used to pronounce it wrong on a regular basis and were unable to find my name on a computer/list/whatever until I spelt it. These days I can't remember the last time someone got it wrong. I still automatically spell it for people who are looking up my name on a computer/list/whatever but I reckon I could have stopped doing that quite some time ago with no negative consequences.
That said I do occasionally get emails where people have used the surname as a forename. For a while there was even a person who addressed me by my forename in face to face conversation but by my surname in emails. I waited for this person to realise their error, which they did and they apologised. I found it rather amusing!