Can I use an RX switch to trigger a QEL?

This is generally not recommended, but would depend on the desired description of operation of the opening.

For most QEL/MEL applications;
If an RX switch is used to trigger the operation, the motor retracts both the latch and the pushpad.  
Because the pushpad is held depressed by the motor, the RX switch maintains an active signal. 
Therefore, the motor will not release creating an infinite loop.
 
The Von Duprin QEL-L option retracts the latch without retracting the pushpad so it would not create the infinite loop described above.
 
The description of operation could lead to using a different product or might require a custom wiring diagram.

DISCLAIMER:

INFORMATION PROVIDED THROUGH THIS SITE IS PROVIDED TO YOU AS IS WITHOUT ANY EXPRESS REPRESENTATIONS OR WARRANTIES OF ANY KIND, AND WE MAKE NO REPRESENTATION OR WARRANTY THAT THIS SITE(OR ANY INFORMATION PROVIDED IN RESPONSE TO YOUR INQUIRY), WILL BE ACCURATE, COMPLETE, OR ERROR-FREE.

YOU AGREE THAT YOU MUST EVALUATE ALL INFORMATION AND RESPONSES, AND THAT YOU BEAR ALL RISKS ASSOCIATED WITH, THE USE OF THIS SITE, INCLUDING ANY RELIANCE ON THE ACCURACY,COMPLETENESS, OR USEFULNESS OF ANY INFORMATION OR MATERIALS MADE AVAILABLE THROUGH THIS SITE.