I have read a manga called Dragon Ball AF by Toyble and I wonder if it is a continuation of the Dragon Ball series?
No, it isn't included in actual series. It is as you can say a fan-made because DBZ was off for so many years and fans were excited for any new glitch that this universe makes. The latest series is Dragon Ball Super.
No, it's fan made, it's not supported by any of the official owners of the Dragon Ball franchise, and it's been denied by 2 owners as well. Along with the lack of merchandise, and lack of advertising, I think that is enough evidence to say it is fake.
proof/support for claim: http://dragonball.wikia.com/wiki/Dragon_Ball_AF more proof/support : http://thedaoofdragonball.com/blog/fans/dragon-ball-af-explained/