In order to cost salaried staff as your business would expect to see it in timesheets and reports, you'll just need to configure how many hours they are contracted to work in a pay period.
If all salaried staff are expected to work the same amount of hours, you can configure this in General Settings:
Then, under the Salaries tab, enter the amount of hours to apply to all staff:
What this means, is that if salaried staff work less than the amount entered in a pay period, their salary will be costed less until Leave or TOIL/RDO is entered to bump it back up.
Alternatively, if different salaried employees in your business have different hours, you can set this on their profile.
First you will need to enable Advanced Payroll by going to Settings > Add-ons > Power-ups:
In the Advanced Payroll Fields tab, click to Enable advanced payroll fields power-up and Update settings to save:
Then head to Staff > My Team > click on the relevant employee > under the Payroll tab > Expected hours in a week/fortnight:
Entering this number on the profile will override the number enter in Settings.