Step 1: SRP works during protein synthesis to pause translation briefly once a signal sequence appears, then dock the ribosome-mRNA-nascent chain complex onto the ER membrane through the SRP receptor.
This particle is not a pure protein or pure RNA molecule, it is a complex of 6 different protein subunits wrapped around a single RNA scaffold known as 7SL RNA in eukaryotic cells.
The bacterial counterpart is much simpler with far fewer proteins and a smaller RNA called 4.5S RNA, so that composition does not apply to the eukaryotic system asked here. Answer: 6 polypeptides and 7 SL RNA.