Hi there Jimi,
If you post your email address i can provide you with a spreadsheet that will proportion bets for dutching and it incorporates kelly staking per runner
But its essential that you have two sets of past results for it to work, your strike rate and payoff for each runner eg 1st 2nd 3rd 4th 5th 6th etc etc, the sheet details down to 8 runners so if you have that info it will work wonders...