I have a membership to TheGrint. They have a place for rounds attested. Since the guys I golf with aren't members and I will not ask them to verify a round via an email, I have 0% attested. If I play a solo round I count it as a practice round. My handicap although official shouldn't be any different than a solo round. I can't prove it wasn't solo other than my integrity. If my integrity is good enough for 0% attested rounds, it should be good enough for a solo round.