The percentage liability staking plan is identical to the fixed liability staking plan except that the liability is linked to a percentage of your bank.
For instance if, your start bank is £100 and the percentage liability setting is 5% then your liability will be £5.
If the bank increases, so will your liability. If the bank decreases, your liability will also decrease.

In TSM there are several further options including a ratchet mode.

Percentage Liability Settings

Windows Desktop TSM Version 6.0

Evaluation version of TSM is restricted to 10 bets at any one time. No time restrictions in place. 

Web Based Version - TSMapp 5.8

Login as Demo User. Restriction of 10 bets at any one time.