Yes, if you need to increase on every row, then you have to increase on the purl side, as well. You can do a M1 purlwise, or purl into the front and back of the stitch.
If a pattern has you increase on every 4th row after that, then it would work out that you happen to increase on the knit side.
"Trust the pattern!"
Time flies like an arrow, but fruit flies like a banana.
Hop aboard while we follow the cloud-covered van of knitting harmony, man!! Woooo!! --Hedgehog
IngridKH on Ravelry