Can't help you...I don't know about a knitting board. I knit by hand and just count the purl rows...

Just count your rows :)

How do you count the rows still in the Knitting board??

There is ever only one row on the knitting board at a time. The yarn that is around the pegs counts as one row. Then you count how many "V"s below that (kind of looks like braid) and that is how many rows you have. You may have to stretch your piece a bit to see them all, especially if you are at the beginning. An easier way would be to make a mark on a piece of paper each time you finish a row.