In situations where the internal audit activity lacks specific financial accounting knowledge for certain audit projects, implementing a guest auditor program is a strategic approach. This program allows the organization to bring in external experts or auditors with specialized knowledge on a temporary basis to address the specific needs of the audit. This approach provides the required expertise without the long-term commitment of a full-time hire, ensuring flexibility and immediate enhancement of the audit team's capabilities.
References:
* The IIA Standards: Standard 1210 - Proficiency: "Internal auditors must possess the knowledge, skills, and other competencies needed to perform their individual responsibilities."
* IIA Practice Guide: "Guest Auditor Programs": Discusses the benefits of bringing in external experts for specialized audit needs.

The most appropriate idea to include in the CSR policy is that management is responsible for ensuring that the organization's CSR principles are communicated, understood, and integrated into decision-making processes.
This aligns with good corporate governance practices which hold management accountable for embedding CSR into the corporate culture and daily operations of the organization, thus ensuring its effective implementation across all levels.References: Corporate governance and CSR integration best practices as documented in business management literature.