No, the institutional costs are not supposed to cover any recruitment since this is not the aim of the action. The RISE action, as all other EU grants, is based on the principle of co-financing. Based on this principle the beneficiaries must co-finance the action by supporting the costs not reimbursed by the EU (in that case, the costs of newly recruited staff if necessary for the action). RISE is not supposed to cover 100% of the costs required to implement the action but only 100% of the eligible costs defined in the GA.
Subcontracting the activities of the action is not possible within RISE (the relevant Article 13 of the grant agreement on the "IMPLEMENTATION OF ACTION TASKS BY SUBCONTRACTORS" does not apply to any MSCA). http://ec.europa.eu/research/participants/data/ref/h2020/mga/msca/h2020-mga-msca-rise-multi_en.pdf