pdfToolbox 11 introduced a new Process plan step 'Rename' which, as the name suggests, renames the current PDF in the Process plan workflow.

1. Prefix: A defined Prefix is prepended to the PDF file name
2. Suffix: A defined Suffix is appended to the PDF file name
3. Replace file name with Prefix and suffix: If set, the current file name is not included in the new file name, i.e. the new file name will be Prefix + Suffix
4. Overwrite existing file: If set, the destination file is overwritten, if it exists

So a setting like the one above would add "_processed" behind the file name, but before the file type suffix.

Using a file called "Yummy_Pumpkin_Yoghurt_x.pdf" would result into "Yummy_Pumpkin_Yoghurt_x_processed.pdf" like on the screenshot of the result dialog below: