HSA distributions (i.e., when money from your HSA is spent on medical expenses) are not directly reported on your return. Instead they appear (if you receive a 1099-SA and entered it as for medical expenses) on line 15 on form 8889.
The tax benefit for HSAs is when you contribute to an HSA - the contribution is either excluded from income or deducted (depending on how the contribution was made). The trick is that when you spend this tax-free money on medical expenses, it's still tax-free.
HSA expenses will not appear on Schedule A.