i would like to try rocket pool.
But I am hesitate to buy RPL, because it introducses another risk. 
Will there be any chance to post collateral in another way?

Right now you can borrow the RPL if you want to avoid exposure, or alternatively: wait for the Saturn upgrade when minipools *without* RPL-bond will be enabled 👍More info about the tokenomics rework here:

Right now you can borrow the RPL if you want to avoid exposure, or alternatively: wait for the Saturn upgrade when minipools *without* RPL-bond will be enabled 👍More info about the tokenomics rework here: https://rpips.rocketpool.net/tokenomics-2024