MarkBerthelemy Hi,
first I need to establish your current configuration and workflow.
You mention you can enable a filter. That means, you are using a Merlin Project (not Express) on a Mac or an iPad (not on iPhone).
Also... the filter 'with resource' implies you are exporting the Work breakdown view.
You ask:
I'd like to send a PDF to each resource in the project, showing when they will be needed.
There are various ways to do so. For example as you are doing right now, by enabling a filter in Work breakdown.
Other possible ways I can think right now:
Switch to an Assignments view. Edit the filter 'Selected Resource'. Select the Resource you need its assignments from. Enable the Filter. Export the View. Repeat.

Use the Details view. Select on the main view (top) a resources view. Select on the details view, any view you want to export (that could be Work breakdown or Assignments). Select on the top view the Resource you need for the export. => see in the details view only its scheduling items. Click any row of the Details view, export.

Select another Resource on the top view, click a row in its Details, export now for this resource.

I personally find the approach with the Details view to be quicker than editing a filter. You can pick the workflow you like best.