Add the rune bars to your metal bank. Use an anvil such as those located in Artisans' Workshop to smith rune knives. Each rune bar produces 25 knives - a profit of 6,070. You can queue up smithing multiple rune knives by right clicking the anvil, choosing "open smithing interface" and selecting rune knives until you have a full inventory of unfinished smithing items. You will then start to smith the knives, automatically starting to smith the next unfinished item as each is completed.
Although smithing rune knives only requires level 50 Smithing, level 59 Smithing is recommended in order to create each unfinished smithing item with the highest possible heat available, maximising the number of knives smithed per hour.