Supplementing with formula?

Anyone feeding baby a mix of breast milk and formula these days? My baby is EBF (almost five months) but I’m out of frozen milk and I hate pumping, so I’m thinking of getting some formula for when I leave her for a few hours with a sitter or my husband. Has anyone else added formula late in the nursing game?

Update: Just tried some formula as a trial run before bedtime and she loved it! Didn’t seem to object at all. Glad to have an alternative for when I’m away from her for a few hours. 💛