There are 3 known Dutching techniques.

Bet to price.
(Your first example)
Price is divided into set take out amount.
The outlays & profits vary.

Bet to set profit.
The outlays vary but profit stays the same.

Bet to fixed outlay.
The outlay stays the same but profit varies.

One can Google free Dutching programs to do this for you.
Such as Ozracetools.


Another approach is , 60/40 Split.
60% on the shorter price & 40% on the longer price.
This can be good in such that not too much is put on the really short priced runners.
One tends to make more profit with this approach when the longer price gets up.
The min price to break even is $1.67

60/40 Example
Fixed 10.00 outlay.
1.66 x 6.00 = Ret 10.20 = .20 Prof.
6.50 x 4.00 = Ret 26.00 = 16.00 Prof.

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Cheers.