How can I record an offline contribution with multiple line items?
Create a Price Set for contributions pointing to the multiple funds needed. Each fund should have a price of 1.00.  You could include additional funds besides the two in question so that the Price Set is ready to be used like this in the future for other potential donation splits.
If the donation needs to be attributed to a certain contribution page, create that contribution page.
Enter a 'New Contribution' under 'Contributions' menu.
Once the price set is created, next to the amount field, you should have the option to choose a Price Set.
Choose your new price set, and split the donation as needed to each fund.
Enter the check info and other pertinent contribution info.
Pick Contribution Page under 'Additional Details' if needed.