  We prove an equivariant Riemann-Roch formula for divisors on algebraic curves
over perfect fields. By reduction to the known case of curves over
algebraically closed fields, we first show a preliminary formula with
coefficients in Q. We then prove and shed some further light on a divisibility
result that yields a formula with integral coefficients. Moreover, we give
variants of the main theorem for equivariant locally free sheaves of higher
rank.
