What I would recommend is take your seeds and put them in soil as others have mentioned.
Take some real dirt, combine it with promix, and mix about 35% dirt with 65% promix (Fertilizer free mix is best for seedlings).
If your able to sift your promix before you combine it with soil, I would recommend it as you don't want pieces of anything in the soil blocking your sprouting seed from finding light, take a 1/4 inch wire screen and build a wooden box frame (2x6" lumber works good) to filter your soil through, then slowly add the promix to the screen box (agitate by hand) and have a tray beneath to collect the mixture below, and then collect and remove all the thick and larger pieces from the screen, and repeat until enough of the purified mixture is collected below, then later on reuse the larger bits at the bottom of a container or bucket when you repot your plants up.
You could also filter the dirt through a screen also, I've thought of purchasing a stainless steel screen for this very purpose myself, as the galvanized screen I'm currently using doesn't handle dirt so well, promix is fine but dirt grinds down the galvanisation and so forth, no biggie I just mix by hand usually.
If your worried about pests in the soil, just get a large container that you could heat over a stove like a canning pot with a lid and heat the soil to 160-180 degrees for 30 mins to steam sterilize it, you will have to add mycorrhizal fungi back to the soil if taking this route as it kills some beneficial organisms also.
Take the cup or container that you are using and fill it 70% full to the top with your dirt and promix blend, place your seed in the container, then take your screened promix that you collected and cover the seed with it about just a hair less than half inch of the mixture, lightly tamp the soil down with just maybe an oz or two of pressure, then take a spray bottle the has zero chemicals ect, new bottle preferably and add 10% hydrogen peroxide with 90% purified or distilled water, the lightly mist the soil, if your not sure about the weight, take another cup that has the same amount of dirt and get a feel for how heavy each cup is as you water the cup containing the seed, when I do my seeds I take about 5mins to feel for how heavy each cup is, usually 15 cups or more depending on what I'm planting, but you do not want to completely saturate your soil til it drains, if you do over saturate it can lead to a drowned seedling, adding water to the soil is a skill at this stage, but a worth while skill to learn, basically you want your soil moist all the way through but not dripping wet, because dripping wet can take more than 5 days to dry and by that time you can have a sprouted seedling that cannot breathe through the saturated soil, and then dies, so use caution, if you like take a cup and completely saturate it , let it drain for 30mins or so, then you would have a dry cup, and a saturated cup to judge how much water you have added, then you could find a happy midway level that can offer ideal conditions for your seeds to sprout inside of.
In this way your seedlings will have a light fluffy top layer to push through, much like seedling started mix, but much more enriched because of the extra Ingredients that are found in promix, then when the seed sprouts it's root will find the heavier soil below which it will grow into, plus this method allows you to see the soil crack open as the seed germinates, and if necessary you can help the seedling find its way to the top/light and gently help remove some dirt so that it can start the photosynthesis process and the stalk will start turning green and so forth.
Once the seed sprouts if no humidity dome or whatever is in place I would add one for about 16-24 hours, usually once the seedling is out of the white stage and starts to gain some color is when it's safe to remove the cover, or when you see the second set of leaves emerging and so forth, some people leave a dome on for more than 48 hrs, but I've noticed stretching and not as ideal growth from leaving it on longer than 36hrs.
(I dislike plugs personally, and 100% peat plugs are terrible for germination compared to real soil/promix blend, I don't recommend them in the slightest for any type of growing personally, I have never used rapid rioters so I cannot say for certain but I don't believe I would expect much from using these besides convenience, no offense.)
Anyways happy growing let me know if you have any questions... cheers.