Type your message in a raw file (.txt with notepad). The files's size must be below 190 bytes (including spaces !)

Then convert the text file into an .INC file (it's a collection of RETLW instructions with symbols) using the script conv.linux.sh (I used bash and dd under Windows to ease the pain)

Then include the .INC file in the main morse10F.asm file (change the filename as needed)

Assemble with MPLAB.

Flash the PIC.

Check it works as expected.