How can we stop RSM from ripping investors off?

Firstly I must say that I don't entirely agree with your premise. I believe the FCA have insisted on AML checks, RSM have sought advice on this from a legal firm so are presumably following the advice. Also, in general terms I don't see much evidence of RSM doing unnecessary things or trying to drag out the administration. However, that aside, RSM fees are one of the few things the Creditor’s Committee members are supposed to have oversight of, so it would probably be a good idea for them to take this up on behalf of ALL investors.

Perhaps it should also be noted that RSM stated in their official Joint Administrators' Proposals and Report dated 15 July 2019

“Joint Administrators' remuneration, costs, expenses and creditor decisions
……
Details of the Joint Administrators' remuneration, costs and expenses are set out below, and in the attached Appendices. In the event a Creditors' Committee is appointed (which is expected), it is for the Creditors' Committee, to determine on what basis the administrator is to be remunerated”

And

“In the event that a Creditors' Committee is not appointed, creditors are asked to approve the following::
……
The Joint Administrators shall be authorised to draw their remuneration based upon time costs limited to the sum of £1.025m (plus VAT) for the first 12 months of the Administration, in accordance with the attached fee estimate.”

My bolding. Thus, I would certainly not expect a CC that is representing the interests of all investors to agree to something in excess of that fixed first year fee amount.

There was a recent Creditors Committee meeting but I have had no feed-back on that from anyone, and as their members here (Monetus and wuzimu ) have not commented about it, I am considering contacting RSM about this soon if they don’t produce any minutes.