You cannot configure premiums for working hours (holidays, weekends, night shift) yet.
You have two ways to record them:
1) Have employees record additional hours
If you grant a 50% weekend premium for weekends, employees can simply book 50% more time than worked. If an employee works 4 h on a Sunday, they simply enter 6 h of working time instead of 4 h. In the comment, they can note that the recorded working time includes a 50% premium.
2) Category for premiums
You can define any categories for time tracking, and employees can book against them. For example, you can create a category “Weekend premium” and a category “Holiday premium”. Employees can then record their actual working hours as usual and, in case of weekend work or holidays, book the time to one of the two categories.
At the end of the month, you can evaluate the entries and calculate the corresponding premium for all entries in the Holiday premium or Weekend premium category. The easiest way to do this is to export the report to Excel (in almost all views in Timebutler there is a “Download” button that lets you download the list view as an Excel file).
To create categories, log in to Timebutler as an admin, click “Settings > More..” at the bottom left, then “Time tracking” on the right. Now click the “Categories” tab.