Allocate overhead project costs to billable projects by "% of revenue"

Summary

Allocate overhead project costs to billable projects by "% of revenue"

Content

We have a requirement to allocate overhead project costs to billable projects by "% of revenue". I have had a look through the project allocation rules UI page and I don't find a suitable basis method. I've seen client extensions as value but I couldn't find any suitable literature in Oracle Support knowledge hub to gauge an understanding about its suitability.

Has any one implemented allocations using "% of revenue" as a basis or any suggestions using client extensions to achieve this requirement?

Appreciate your suggestions...