If you receive an automatically generated pdf receipt after payment that means your payment was accepted. Then, when you send the RPRF receipt by email, you normally receive an auto response acknowledging the reception of your email ( that included your receipt). In respect of adding a line on Ecas, there is no line specifically for RPRF but for my case the visa office asked me to pay RPRF at the end of the process and I paid and sent them the receipt by email, then next the third line and DM were added together at the same time on ECAS. I do not know if this process dictates a positive sign but I am hoping to receive PPR soon ( hopefully and optimistically)