In order to book time against a project you need to have roles with rates created in the same currency as the project currency.
Note: you will have created the necessary currency prior to creating the role(s) leveraging this currency.
Create role(s) for each currency
In the same way where you create roles with selling and cost rates using the organization base currency, you can create roles using different currencies. This way, you can identify which roles relate to which project and currency.
Go to the Settings (gear icon) and choose from the menu Roles and rates:
In the Roles page, click the Create role button:
The Role dialog box appears:
In the Role field, create the desired role. I.e., Consultant.
In the Currency drop-down list, select the desired currency. Then, add the Selling and Cost rates for the hourly rate for the role
When you create a new project and select the currency, only roles related to the currency will appear when assigning to the project.
Click Save and display the role in the list:
Repeat these steps for all project roles using the new currency.
Assign roles with new currency
Once the roles are created, they need to be assigned to your team members.
Go to the Settings and choose from the menu User management:
In the Users page, either invite a new user(s) or select an existing user and the assign your role linked to the currency by checking the boxes:
Click Save. The new roles will be listed on the Role field.
Click Save to store all changes.